tag:blogger.com,1999:blog-71157201694933436492024-03-05T16:38:47.934+10:00The Beat SheetThe Beat Sheet is a blog about insect pest management issues relevant to Australia's northern grain region of Queensland and northern New South Wales. This team blog is updated by entomology staff from Queensland Primary Industries and Fisheries. Their contribution is supported by funding from the grains and cotton industries.BigBughttp://www.blogger.com/profile/11764696091701617022noreply@blogger.comBlogger47125tag:blogger.com,1999:blog-7115720169493343649.post-72136359309806248732009-10-12T08:12:00.005+10:002009-10-12T08:20:19.040+10:00White heads and stem borer in wheatEvery year we receive reports of white heads in wheat, and while there are several possible causes of this symptom, one suspect implicated in the crime is a small stem boring larva called <em>Ephysteris silignitis</em> (Turner) belonging to the moth Family Gelechiidae.<br /><br />Rod Collins and Hugh Brier did some investigative work back in 1998. They reared a couple of larvae through to the adult moths and had them identified by ANIC.<br /><br />Rod Collins made the following observations: “The damage was usually confined to a single tiller per plant at a relatively low incidence through fields. Infected tillers seemed to have flowered normally, but soon after flowering the stem upwards from the last node (and including the head) died and was white in colour with no grain in the head. From a distance, these symptoms appeared to be the same as those of crown rot. However, infected tillers were green and apparently healthy from the last node (including the flag leaf) down. On closer examination, a small entry hole about the size of a pinhead was evident usually at or just below the first node up from the base of the plant. In some cases an exit hole was noted just above the last node.”<br /><br />“When the stem was split open, you could follow where the larva had been up until the last node, where it was often found feeding on the tip of the stem just above the last node. In some cases, the larva had chewed through the tip and continued to move upwards towards the head. It appeared that once the stem began to dry out, the larva would bore a hole in the stem and exit. Only one larva was found per stem in all the plants that I saw.”<br /><br />It seems not much is known about this species. It is believed to be a native species, one of three in this genus found in Australia. <em>Ephysteris promptella</em> is recorded as a pest of sugarcane in Australia. <em>Ephysteris silignitis</em> occurs widely in Australia south to about 35 degrees south and is thought to be confined to Australia. It is in the wettest parts e.g. Brisbane and Mt Bellenden Ker and the driest. It is common at Alice Springs. It was suggested that it may feed on grasses but there was no evidence. <div><br /><br /><div></div><img id="BLOGGER_PHOTO_ID_5391470034598502034" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 282px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGH5VE2eVv4Qi3bWopL59j-Q9fCIioi9f4ufLJWbEGC5gy5LBgwFsXqOMA6YDlwPpyAvpewpQuOKRyboCpD6wPZEWSOTpF5A_TkpKB_e9lnc50REFlumnIecoACY7bgaxuv2iuHttcEWdR/s400/DSCF2166_COMPRESS2.jpg" border="0" /> Stem borer larva in wheat (Photo by Iain Macpherson)<br /><br />At this stage the reports of isolated ‘white heads’ do not represent economic loss, but this stem borer is something to be aware of if those scattered white heads are observed in fields. There is no registered chemical control.</div>BigBughttp://www.blogger.com/profile/11764696091701617022noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-23674913214809423772009-10-09T08:13:00.005+10:002009-10-09T08:21:52.498+10:00Recce for armyworm in winter cerealsThe quick finish for winter cereals this season has resulted in the majority of crops escaping infestations of armyworm. Headers are already into some fields, but there are reports of armyworm making their presence felt in some of the later crops.<br /><br />Being aware of their presence is one thing; whether to intervene is another.<br /><br />In some late crops starting to turn, the presence of up to 12 small armyworm larvae per square metre need not necessarily sound alarm bells. This situation requires careful and regular monitoring, but there is every chance the crop will make it to harvest without the need to control armyworm.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3Nh3NMdDK8bF-CmalEbjPEjRqdfQhpMr16Eik9-7e7R6dKTjYU_4vEJ1mzWPGljTYJARM83QMbdkWVDVhskd161_LDuMgWNk2mxZa1r-kk83Wlb32q95VSfUHItf1FNbg9ml-wj8O18qZ/s1600-h/armyworm+headcutting.JPG"><img id="BLOGGER_PHOTO_ID_5390356824077088610" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; WIDTH: 259px; CURSOR: hand; HEIGHT: 400px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3Nh3NMdDK8bF-CmalEbjPEjRqdfQhpMr16Eik9-7e7R6dKTjYU_4vEJ1mzWPGljTYJARM83QMbdkWVDVhskd161_LDuMgWNk2mxZa1r-kk83Wlb32q95VSfUHItf1FNbg9ml-wj8O18qZ/s400/armyworm+headcutting.JPG" border="0" /></a>If however, the crop lingers and the armyworm develop into medium and large larvae, there is a risk, particularly with barley, that head cutting will result in high yield losses. In this situation, quick action may be required to control armyworm and prevent losses.<br /><br />The key points are<br />1) to be aware that armyworm are present and<br />2) to inspect regularly as the crop approaches maturity so that appropriate action can be taken if head cutting occurs.<br /><br />For more information on armyworm, see the posting made on 20 October 2008.<br /><br /><p><br /></p><br />Photo: Watch for the early signs of head cutting.<br /><br /><br /><br /><br /><strong>Reminder: Last date for Steward® EC use on chickpeas is 15 October</strong><br /><br />Winter pulses have had their expected share of helicoverpa infestations over recent weeks and most crops have been sprayed to control grubs. Strategies to minimise the risk of insecticide resistance are available. The following points should be observed.<br /><br />Under the Insecticide Resistance Management Strategy (IRMS), the last use of Steward® EC for Central and Southern regions is 15 October, while the last use date for Northern (Central Queensland) regions (15 September) has long passed.<br /><br />Grower and consultants are also reminded that for all pulse crops, not more than one application of Steward® EC per field is allowed for the crops entire growth cycle.<br /><br />Access the full IRMS for 2009-10 on the Cotton CRC website:<br /><a href="http://www.cottoncrc.org.au/content/Industry/Publications/Pests_and_Beneficials/Insect_Resistance_Management.aspx">http://www.cottoncrc.org.au/content/Industry/Publications/Pests_and_Beneficials/Insect_Resistance_Management.aspx</a>BigBughttp://www.blogger.com/profile/11764696091701617022noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-33942059781270814062009-09-10T08:16:00.009+10:002009-09-10T08:30:36.985+10:00Resistance Update on the RoadThe Resistance Roadshow visited regional areas during late August and presented the latest resistance monitoring results for a suite of important pests. Presentations covered resistance to conventional insecticides in cotton aphids, mites, silverleaf whitefly and helicoverpa, and helicoverpa resistance to the Bt toxins in Bollgard II.<br /><br /><br /><img id="BLOGGER_PHOTO_ID_5379595821025758770" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 240px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKuIw_9m-SltfFV_-rgdiTPnYX5zUAr7damGv-99RUXQ40NnmJ-O0_SH_oTpMv9qpyYNICpChdGSkM8xSirpQSK2m5C___27XFrI6ArFXt6fLkMD8xSEns-tTUabyIR2ucZb0qsIlxOQ_s/s400/TIMS+Roadshow+20090826+001+Cropped.jpg" border="0" /><br />Photo: Downs agronomist Bernie Caffery (right) discusses resistance with Sharon Downes and Grant Herron at the Dalby Resistance Roadshow.<br /><br /><strong>Aphids and mites</strong><br />Dr Grant Herron, Industry and Investment NSW based at Menangle, presented his latest results for cotton aphids and mites. Cotton aphid resistance to neonicotinoids was detected at many locations during the 2008-09 season and was associated with product failures. Grant suggests that neonicotinoid seed dressings are influencing the development of this resistance. His recommendation is to try to avoid foliar neonicotinoids for aphid control if a neonicotinoid seed dressing has previously been used that season. However, if they are sprayed for aphid control Grant highlighted the need to alternate chemical groups for seed dressing and first foliar spray.<br /><br />Fortunately there appears to be no cross resistance to pirimicarb, organophosphates and endosulfan and these products should perform satisfactorily against neonicotinoid resistant strains. Cotton aphid resistance to Pegasus® was reported for the first time.<br /><br />Resistance was detected to Comite® in two spotted mite populations. This is one of the most widely used products for mite control in cotton, so the detection of resistance is a serious concern.<br /><br /><strong>Whitefly</strong><br />Results of resistance testing for silverleaf whitefly (B biotype) by Zara Ludgate, QPIF Toowoomba, indicate no immediate concerns for the two key products, Admiral® and Pegasus®, used to manage this pest in cotton. Surveys of cropping regions during autumn and winter 2009 have so far failed to reveal any Q biotype Bemisia tabaci that was first reported from north Queensland in late 2008 and north-western NSW in 2009.<br /><br /><strong>Helicoverpa</strong><br />According to Dr Louise Rossiter, Industry and Investment NSW, Narrabri, resistance in <em>Helicoverpa armigera</em> to most conventional insecticides has declined or stabilised. Areas of concern are the continuing high level of resistance to older pyrethroids and moderate resistance to the carbamates. Field performance of these products against <em>H. armigera</em> may be highly variable. There are no conventional insecticide resistance issues associated with <em>H. punctigera</em>.<br /><br />The 2009-10 Insecticide Resistance Management Strategy is available on the CRC website:<br /><a href="http://www.cottoncrc.org.au/content/Industry/Publications/Pests_and_Beneficials/Insect_Resistance_Management.aspx">http://www.cottoncrc.org.au/content/Industry/Publications/Pests_and_Beneficials/Insect_Resistance_Management.aspx</a><br /><strong></strong><br /><strong>Bt resistance</strong><br />Dr Sharon Downes, CSIRO Narrabri, and Kristen Knight, Monsanto Australia, outlined the results for resistance testing to the two Bt toxins. While the frequency of Cry 1Ac resistance alleles remains at very low levels, the frequency of Cry 2Ab resistance alleles in populations of <em>H. armigera</em> and <em>H. punctigera</em> are higher than expected. Changes in the frequency of resistance alleles are being closely monitored as further upward movement in resistance frequencies could be a trigger for changes to the Resistance Management Plan which aims to preserve the usefulness of this GM technology.<br /><br /><br /><img id="BLOGGER_PHOTO_ID_5379596704447690738" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 267px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2fK2_jDsUMneRS9IE37hS0KkSBusoPTEttCf1f1N6M-kSAIw71_JVP566qdZ_v5Dfd0h6qk-JuCJyd-4rwBAAnup7wnwOSNlHHQxagjnE0h3kaJQ-rmJdn6yzeEKS_VYhD2uMU5VM78MC/s400/TIMS+Roadshow+20090826+003+Cropped.jpg" border="0" /><br />Photo: Kristen Knight (left) of Monsanto discusses Bt resistance with Kate Charleston of QPIF at the Dalby Resistance Roadshow.BigBughttp://www.blogger.com/profile/11764696091701617022noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-52038079458034997832009-08-07T12:44:00.013+10:002009-08-07T14:10:14.175+10:00Refresher on managing helicoverpa in chickpea<div><span style="color:#000000;">With the approach of spring, helicoverpa start to become active. In CQ, chickpea crops are attractive to moths, and it is timely to revisit some of the key points related to making decisions about control of this pest in crops.<br /><br />There is a technical brochure available at the QPIF website, which provides a comprehensive overview of sampling and the use of economic thresholds to guide decision making. The brochure can be accessed via this link:</span> (<a href="http://www.dpi.qld.gov.au/cps/rde/dpi/hs.xsl/26_6821_ENA_HTML.htm">http://www.dpi.qld.gov.au/cps/rde/dpi/hs.xsl/26_6821_ENA_HTML.htm</a>).<br /><br /><span style="color:#000000;">In this article, I wanted to discuss a couple of the recommendations which some growers and agronomists have found a bit challenging. The first is adjusting larval density estimates to focus on those larvae that will cause damage.</span><br /><br /><span style="color:#000000;"><span style="color:#3333ff;">1) <em><strong>Excluding very small larvae from threshold calculations</strong></em>.</span> </span><span style="color:#000000;">Estimating the number of very small larvae (VS) is time consuming to do in the field, and the accuracy of the estimate can be affected by the age and condition of the crop (figure 1). Whilst VS larvae are indicative of the size of the potentially damaging population in 2-3 weeks time, they are not relevant to a decision about controlling the current population to prevent yield loss.</span><br /><br /><p><img id="BLOGGER_PHOTO_ID_5367048978636664098" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 234px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhL0COyOT7FtIBDFRxlmQO1fZSu1YIwEMVplpAHZnoFSr8TV7QNhwoQcG7DkPC163PtkENF5ODkQQdOBKy8YG90WfEQcoxt5CHyLB8j-kmIQGQb6KeghK9cL11-xbi0oJ2IwPsootWl7bC2/s400/chickpea+1.jpg" border="0" /> </p><p><em><span style="font-size:85%;color:#003300;"><img id="BLOGGER_PHOTO_ID_5367068880192603090" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 273px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGBkRSw-sHJ7eamBnTwm73sWuF68Ee2Xwv42vH6-HOCACus3R8We8LoxHbC4ShYBKJJTUYSqsEYYrOvRbkFWjMyunSsru81QZqe4BrDryy6vGBlTW9aKfPAS2SAMdY1IDewrYjfGsAEEsg/s400/chickpea6.jpg" border="0" /></span></em></p><p><em><span style="font-size:85%;color:#003300;">Figure 1. Comparison of visual, beat sheet and absolute sampling for helicoverpa larvae on (a) dryland chickpea at late flower - pod fill, and (b) irrigated chickpea at mid flower to early pod set. VS=very small, S=small, SM=small-medium, ML=medium-large, L=large larvae. (Source: Melina Miles, 2004)<br /></span></em><br /><span style="color:#3333ff;"><em><strong>2) Applying a 30% mortality factor to small larvae</strong></em>. </span><span style="color:#000000;">Essentially, applying mortality is acknowledging that a proportion of the population will not cause any yield loss because they do not survive to become medium and large larvae. Natural mortality is likely a result of dislodgement from the plant, disease, cannibalism, and predation. Remember that 80-90% of crop damage is caused by medium and large larvae. </span></p><br /><p><span style="color:#000000;">This recommendation is based on trial work, largely in CQ, in which we followed infestations of helicoverpa and determined what proportion of the starting population of small larvae survived to large. The level of survival was variable between fields, but on average we determined that 70% of small larvae died before they reached large. In making a recommendation to include</span> <span style="color:#000000;">natural larval mortality we have been conservative, using only 30% mortality (the highest level of survival we found at any of the sites we monitored).<br /><br />In practice, in calculating how many larvae per m2 are likely to contribute to yield loss in the crop if left untreated, the following equation be used: </span></p><br /><p><img id="BLOGGER_PHOTO_ID_5367049667586094450" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 357px; CURSOR: hand; HEIGHT: 66px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiu8LCt0jvROczof7P1vmZa_1rmW6jYkVY8v6jYNb7LkZMYzrMaPOz6J4K4xIVuZbddXeGgqOyNB9UD3GuWowpYb3GvtqtKZlntkIhZ5ZLyEstxR6d5CdlPnglt_OA4WHl1xMUC0mZv0A_S/s400/equation+chpea.jpg" border="0" /> <span style="color:#000000;">Where S = small, M= medium and L= large larvae</span><br /><br /><span style="color:#3333ff;"><em><strong>3) O</strong></em></span><em><strong><span style="color:#3333ff;">ne</span><span style="color:#3333ff;"> well timed spray should be enough</strong></em>. </span><span style="color:#000000;">The timing of a spray should control larvae before they cause damage, but not simply be applied if larvae in the crop exceed threshold. Infestations of helicoverpa in vegetative and flowering crops have been shown to cause no yield loss in chickpea.<br /><br />A spray may need to be applied during late flowering if targeting small and medium larvae to prevent them causing damage to a podding crop when they are medium-large. However, treating a population to prevent damage to a vegetative or flowering crop offers no yield benefit</span>.<br /><br /><span style="color:#000000;">Trial results show that, in chickpea, helicoverpa larvae cause very little damage to buds and flowers (Figure 2). This is quite different behaviour from that seen in mungbeans, for example, where larvae show a clear preference for buds and flowers. Chickpea leaves appear more palatable to helicoverpa larvae than that of mungbeans. </span></p><br /><p><img id="BLOGGER_PHOTO_ID_5367050177864062098" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 240px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJvCCD9v_03YbiTkPdSlgbRGSmxHlcMmqLWk7-o67ANkLXsmGUjYTNmuYq8Ucgk2meIo9v99LT-5xSOsIEMDqu2YsGwToFQTRMuGconzJSTFP5Cd5pLeLL4_-D0S2cOrcAdsmlhUn-qhIH/s400/chickpea2.jpg" border="0" /> <span style="color:#000000;"><em><span style="font-size:85%;color:#003300;">Figure 2. Feeding preferences of small and large helicoverpa larvae on chickpea.</span><br /></em><br />These observations are supported by yield data from time of spraying trials which shows no significant benefit in yield from applying a spray at flowering. Yield loss starts to occur when larvae are present in podding and filling crops (Figure 3).<br /></span><img id="BLOGGER_PHOTO_ID_5367050526186949170" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 208px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhB1Cvks8nN9IC2uhn63tb_NGEfScGnkod-9-bt0wm1y8giGh9XqOzsJljLgTyH45wvfqDFYKkO8GrbfoNtnv_cDLzPkFrILwrw43Sl4Jd2Q4Z2P1MsP-O_-7uETPtln0Jh3dYdzrvmyDCu/s400/chickpea3.jpg" border="0" /><br /><em><span style="color:#003300;"><span style="font-size:85%;">Figure 3. The impact of helicoverpa on chickpea yield when controlled at different stages of crop maturity. Bars with the same letter are not significantly different from each other.</span><br /></span></em><br /><span style="color:#000099;"><strong>Remember</strong><br /></span><span style="color:#000000;">Only one application of Steward® (indoxacarb) per crop, with a cut off for use of 15 September in CQ, and 15 October in cooler regions. Currently there is no evidence of resistance to indoxacarb in helicoverpa populations from cotton, but there has been no testing of larvae from CQ, or from chickpea. I would encourage you to make collections from chickpea to send to Dr Louise Rossiter, NSW DPI, Narrabri. Contact Louise on 02 6799 2428 or</span> <a href="mailto:louise.rossiter@dpi.nsw.gov.au">louise.rossiter@dpi.nsw.gov.au</a>.<br /></p><br /><p><br /><strong><span style="color:#000000;"><span style="color:#3333ff;"><em>Revised ready-reckoner for calculating the economic threshold</em></span> </span></strong></p><br /><p><span style="color:#000000;"><strong>Economic Thresholds (larvae/m2) for Conventional Pesticides</strong></span> </p><br /><br /><br /><img id="BLOGGER_PHOTO_ID_5367053840362909826" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 437px; CURSOR: hand; HEIGHT: 161px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwVObFISW1akMNUBhny4YEjuk42UB4kh0oedpwudQgRkB_1Nphmxw_1W5zR39S6zVjPrg7HmZtiAIT3RffVRZZgYe3dyGrYlk3F7ZgqYYxHpzGVEv-H82pfMOXbkQvWIswC1UwzgPO9txU/s400/chickpea5.jpg" border="0" /><br /><br /><span style="color:#000000;">Cross-reference the cost of control versus the crop value to determine the economic threshold (ET).<br />If the cost of control = $25/ha and the crop value =$450/t, the ET = 2.8<br />If the cost of control = $10/ha and the crop value =$550/t, the ET = 0.9<br />The lower the cost of control, and the higher the crop value, the lower the threshold.<br /><span style="font-size:78%;">(Table compiled by Gordon Cumming, Pulse Australia)</span> </span><br /><span style="color:#000000;"><br /></span><span style="color:#ff0000;"></span><br /><br /><p><span style="color:#009900;"><strong>Your opinions and experience are important, so leave a comment on this article or helicoverpa management issues.<br /></strong></span><br />Maybe you would like to respond to the following questions:<br /><br /><span style="color:#3333ff;">- How are you calculating your economic thresholds? Are you using the equation suggested by QPIF, or is it close enough to 2 or 3 that you are just using that?<br /><br />- Is the revised ready-reckoner any easier to use?<br /><br />- Would a threshold calculator be a useful tool? i.e. where you put sampling and crop data in (larval number and size, grain price, cost of control) and it calculates the threshold.</span></p><span style="color:#006600;">Article by Melina Miles</span></div>damsel bughttp://www.blogger.com/profile/04266164657823029589noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-19206693770613608712009-08-02T22:58:00.005+10:002009-08-03T09:19:18.981+10:00Winter cereal aphids – background to the potential impact of infestations<span style="color:#000000;">The most critical issues we face in managing cereal aphids currently is the lack of local knowledge about the likely impact of infestations on yield and quality (the damage thresholds).<br /><br />In this article, I will not go over aphid basics i.e. identification and sampling. You can follow the links to previous articles to read about these</span> (<a href="http://thebeatsheet-ipmnews.blogspot.com/2008/09/cereal-aphids-in-wheat-and-barley.html">http://thebeatsheet-ipmnews.blogspot.com/2008/09/cereal-aphids-in-wheat-and-barley.html</a>).<br /><br /><span style="color:#000000;">In this posting, I want to discuss what is known, from overseas research, and what we might draw on from this work to help us make decisions about aphid management and control. This review may provide some useful information, in the absence of any locally generated data on aphid impacts. Surprisingly, there has been very little work done on cereal aphids in Australia.<br /></span><br /><span style="color:#000000;"><strong><span style="font-size:130%;">General points<br /></span></strong>The literature, largely from North America and Europe, indicates that there can be significant differences in the way different cultivars respond to the impact of aphids. For this reason, it is important to use this information as general information that may assist in understanding how your crop may be responding to an aphid infestation. In the absence of local data, it is a useful starting point.<br /><br />Aphids have a requirement for nitrogen (N) to complete development and reproduce. Honeydew is a by-product of their feeding. Essentially aphids compete with the plant for available N, which can impact on the plant in at different stages of crop development.<br /></span><br /><span style="color:#000000;"><span style="font-size:130%;"><strong>Early aphid infestations</strong></span> (from seedling)<br />Root and shoot growth may be impaired as a result of aphids competing for N. Inadequate N for the crop may make the crop more vulnerable to the impact of an aphid infestation.<br /><br />Prolonged infestation can reduce tillering and result in earlier leaf senescence. Controlling aphids generally results in a recovery of the rate of root and shoot development, but there can be a delay.<br /><br /><span style="font-size:130%;"><strong>Late aphid infestations</strong></span><br /></span><span style="color:#000000;">There is no impact on yield after grain has filled and is maturing (soft-hard dough).<br /><br />Infestations that occur during booting to milky dough, particularly where aphids are colonising the flag leaf, stem and ear, result in yield loss. Generally, the distal grains in the head fail to fill. Infestations at this stage in which aphids colonise the leaves, particularly lower in the canopy, tend to result in grain with reduced N (protein) rather than a loss in yield. Aphids are intercepting the N being relocated from leaves to the filling grain.<br /><br />The relative impact of timing and location of infestation makes sense if you review it along with what is known about the contribution of different parts of the crop to yield. The figure below illustrates the contribution of the upper leaves, stem and ear to the yield of wheat and barley (GRDC Winter Cereal Crop Growth Guide 2005</span> <a href="http://www.grdc.com.au/director/events/grdcpublications?item_id=8D607A46EDDFD98A822CFAEC7FCC4EC2&pageNumber=1">http://www.grdc.com.au/director/events/grdcpublications?item_id=8D607A46EDDFD98A822CFAEC7FCC4EC2&pageNumber=1</a>). <div><br /><div><img id="BLOGGER_PHOTO_ID_5365506565108082386" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 218px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhObPCmPy3zKTAW9llYGRPi5JD79613Fc2PoRYzxh79LuRlFwIYNd1wuwILdxEnEVu5vMdI548zwdXAcvNSBvo-Dq-hR4egP8vIYx3kPjQ-DVfu76sQUsUu2MIpcD6ECy6CFO2tIrTIzl5V/s400/Yield+Contribution+Image1.jpg" border="0" /><br /></div><span style="color:#000000;"><strong><span style="font-size:130%;">Ongoing research</span></strong><br />There is currently research being conducted on cereal aphids, by QPIF and the Northern Grower Alliance (NGA).<br /><br />In 2008, initial trial work by QPIF and NGA showed different results (see the GRDC Update, Goondiwindi, 2009 papers for NGA results. Briefly, NGA trial work showed an overall yield benefit of around 10% from using seed dressings containing imidacloprid. QPIF results showed no difference from seed treatment, but a yield benefit where a foliar treatment (pirimicarb) was applied at head emergence.<br /></span><br /><div></div><div><span style="color:#000099;">Article by Melina Miles</span></div></div>bugladyhttp://www.blogger.com/profile/13351824435251392456noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-45907091627953250772009-05-28T14:18:00.012+10:002009-05-28T16:05:10.136+10:00Slaters and other winter cereal establishment pests<span style="color:#000000;">In recent days we have received a number of reports of slater activity in winter cereal crops in southern Queensland and northern NSW.<br /><br />Slaters are not generally regarded as a pest of broad acre agriculture and tend to feed on decaying vegetation and dead animal matter. Overall they perform an important recycling role in the environment however on rare occasions they can also attack seedlings of broad acre crops.</span><br /><div><div><div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhebO8Pqigmyg9qGMq3StfKsKvy25o4DLLzYgwkh-ilRPbBCKE3e0iMBtGO-MmI2ogVfFbPa6QbIZdDh-GcbhfG1oZmFopB-SzWEkndm6HFx2PP-OVhP-tnpsNeeBN-QQY_20aILbi6QfNe/s1600-h/sslater.jpg"><span style="color:#000000;"><img id="BLOGGER_PHOTO_ID_5340731404820799906" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; WIDTH: 300px; CURSOR: hand; HEIGHT: 289px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhebO8Pqigmyg9qGMq3StfKsKvy25o4DLLzYgwkh-ilRPbBCKE3e0iMBtGO-MmI2ogVfFbPa6QbIZdDh-GcbhfG1oZmFopB-SzWEkndm6HFx2PP-OVhP-tnpsNeeBN-QQY_20aILbi6QfNe/s400/sslater.jpg" border="0" /></span></a><span style="color:#000000;">Slaters are woodlice and they are crustaceans, not insects. They have a hard skeleton on the outside and many pairs of jointed legs. The native slater species doing the damage to cereal crops is <em>Australiodillo bifrons.</em> This species has a light brown oval shaped and flattened body with a dark brown stripe in the middle of the back. Both males and females have a characteristic split on the frontal plate. Males tend to be larger than females and can grow as large as 9 mm long and 6.5 mm wide.<br /></span><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjedbBiDzzKkcB5nRo8nNPBd6jLTgmZTF5ZH1xYjq6uEXsyN2p6ZFGY3XYhKXLWcWy3voKZsh9Ri-rV9idMLztzGzWcsjJMJPVGJhP1jCMxFpxcdE1ASgAWg-VT4GUkWpQiEuJXGldt9i3j/s1600-h/native+slater.jpg"></a><br /><span style="color:#000000;">This native slater is commonly found in low lying swampy regions and tends to be more active after rain periods. They need damp conditions and will die if exposed to open and dry situations.<br /><br />Slaters are an agricultural pest in South Africa where they are generally controlled by cultivation. Changing farming practices such as minimum or non tillage seem to have worsened the slater problem, especially if there is also a large amount of stubble present in fields.<br /><br />Slaters are known to do damage to seedlings of wheat and oats and there is also evidence of slater activity in canola in western and southern Australia. It is not known if other crops are hosts for slaters.<br /></span><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgr1Ht0-K-1nzHUsluYA0FPKGBQk9X5rhI5H0o-ci0eOk0qBFp0aj3Nyn1NUBKvPne-sK6e1IR0eF4cYuLgpgrFXftUXiCg42z-gRpneTHeA65AjTimpPBNhExcCoJWNp0OJyIUqDuDBTmN/s1600-h/sslater+damage.jpg"><img id="BLOGGER_PHOTO_ID_5340731499412050194" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 379px; CURSOR: hand; HEIGHT: 305px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgr1Ht0-K-1nzHUsluYA0FPKGBQk9X5rhI5H0o-ci0eOk0qBFp0aj3Nyn1NUBKvPne-sK6e1IR0eF4cYuLgpgrFXftUXiCg42z-gRpneTHeA65AjTimpPBNhExcCoJWNp0OJyIUqDuDBTmN/s400/sslater+damage.jpg" border="0" /></a><br /><strong><span style="color:#000099;">Damage:</span></strong> <span style="color:#000000;">Slater damage looks similar to snail and slug damage with rasping and shredded appearance to leaves. Feeding damage can also appear as irregular patches removed from the leaves resulting in distinctive ‘windows’ of transparent leaf membrane. Thousands of seedlings can be eaten in a short time by swarms of slaters.</span><br /><br /><strong><span style="color:#000099;">Control:</span></strong> <span style="color:#000000;">There are no registered pesticides for the control of slaters in winter cereals. Non chemical approaches such as providing alternative habitats may decrease slater numbers in crops. Shelterbelts containing a complex understorey of vegetation and soil litter may be more attractive to slaters. Such environments also harbour many natural enemies of broad acre insect pests which can also keep slater populations in check.</span><br /><br /><span style="color:#000000;"><span style="font-size:130%;"><strong>Other winter cereal seedling pests<br /></strong></span><br /></span><span style="color:#000000;"><strong>Cutworms<br /></strong>Several species of cutworms attack establishing cereal crops in Queensland and NSW. As their name suggests cutworm larvae sever (cut) the stems of young seedlings at or near ground level, causing the collapse of the plant. </span></div><div><div><div><div><div><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrtoahmaUan8UGG8RUAVDyKLZX9rmYwPt3QYdLcfD0qeX2B72Oq-uVTHTaQXT7ONv9EOvLbXXJtpinfLGSta7D8G81TbDXEtKCsYpYJ9keeI2PWyotKReL4_6TGs3RfsOrynItStYTfwuZ/s1600-h/Insects-Cutworm-Larvae-250.jpg"><span style="color:#000000;"><img id="BLOGGER_PHOTO_ID_5340725379715946978" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; WIDTH: 250px; CURSOR: hand; HEIGHT: 161px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrtoahmaUan8UGG8RUAVDyKLZX9rmYwPt3QYdLcfD0qeX2B72Oq-uVTHTaQXT7ONv9EOvLbXXJtpinfLGSta7D8G81TbDXEtKCsYpYJ9keeI2PWyotKReL4_6TGs3RfsOrynItStYTfwuZ/s400/Insects-Cutworm-Larvae-250.jpg" border="0" /></span></a><span style="color:#000000;">Cutworm larvae are up to 50 mm long, hairless with dark heads and usually dark coloured bodies, often with longitudinal lines and/or dark spots. Larvae curl up and remain still if picked up.<br /></span><br /><span style="color:#000099;"><strong>Damage:</strong></span> <span style="color:#000000;">Young caterpillars climb plants and skeletonise the leaves or eat small holes. The older larvae may also climb to browse or cut off leaves, but commonly cut through stems at ground level and feed on the top growth of felled plants. Caterpillars that are almost fully grown often remain underground and chew into plants at or below ground level.<br /></span><br /><span style="color:#000099;"><strong>Monitoring and control:</strong></span> <span style="color:#000000;">Inspect crops twice weekly in seedling and early vegetative stage. The best time to monitor is late afternoons and evenings when larvae feed. Chemical control is warranted when there is a rapidly increasing area or proportion of crop damage. If distribution is patchy, spot spraying may suffice. Chlorpyrifos and various pyrethroids are mainly used to control cutworm.<br />Cultural control measures include weed control – at least 3-4 weeks prior to sowing.<br /><br /></span><span style="color:#000000;"><strong>Blue oat mite<br /></strong>The blue oat mite is an important pest of seedling winter cereals. When infestations are severe the leaf tips wither and eventually the seedlings die. Eggs laid in the soil hibernate over winter, allowing populations to build up over a number of years, causing severe damage if crop rotation is not practised. <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIFxdJrZX9UmgYLD7VTqZplvhQ0mSZIlcMqOrix87XylWIaaucYdd_BP_uFZGeiYcF-zqjlV0WeG3e-k2qS1VGc8aK0NNzhL41spnc4QbnrONv86srWn8NqcnQH2iAeCsgjb5v_qKIrm_m/s1600-h/Insects-Mite-BlueOat-250.jpg"><img id="BLOGGER_PHOTO_ID_5340734371775975826" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 250px; CURSOR: hand; HEIGHT: 286px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIFxdJrZX9UmgYLD7VTqZplvhQ0mSZIlcMqOrix87XylWIaaucYdd_BP_uFZGeiYcF-zqjlV0WeG3e-k2qS1VGc8aK0NNzhL41spnc4QbnrONv86srWn8NqcnQH2iAeCsgjb5v_qKIrm_m/s400/Insects-Mite-BlueOat-250.jpg" border="0" /></a><br /></span></div><br /><span style="color:#000000;">Adults are 1 mm long and have 8 legs. Adults and nymphs have a purplish-blue, rounded body with red legs. They move quickly when disturbed. The presence of a small red area on the back distinguishes it from the redlegged earth mite.<br /><br /></span><strong><span style="color:#000099;">Damage:</span></strong> <span style="color:#000000;">Adults and nymphs pierce and suck on leaves resulting in silvering of the leaf tips in cereals. When heavy infestations occur, the leaf tip withers and the seedling can die. In canola, leaves are mottled or whitened in appearance.<br /></span><br /><strong><span style="color:#000099;">Monitoring and control:</span></strong> <span style="color:#000000;">Check from planting to early vegetative stage, particularly in dry seasons. Blue oat mites are most easily seen in the late afternoon when they begin feeding on the leaves.<br />Where warranted, foliar application of registered insecticide may be cost-effective if applied within 2-3 weeks of emergence in autumn.<br /><br /><strong>Know your seedling pests</strong><br />Correct identification of pests feeding on cereal seedlings is important as this will influence selection of control options.<br /></span><br /><span style="color:#000099;">Article by Kate Charleston and David Murray<br /></span></div><br /><div><br /><span style="font-size:180%;color:#003300;"><strong>Fleabane alert</strong></span><br /><span style="color:#000000;">Following the recent rain, the first main flush of fleabane for the year will start to emerge shortly. Whilst this weed is often regarded as one of the most difficult-to-control weed, it is much easier to control when it is a small seedling. So, growers need to be alert and think about spraying soon.<br /><br />To assist growers and consultants, the weeds team has recently published a brochure on fleabane, and it is available from the Queensland Primary Industries & Fisheries website</span> <a href="http://www.dpi.qld.gov.au/cps/rde/dpi/hs.xsl/26_4251_ENA_HTML.htm">http://www.dpi.qld.gov.au/cps/rde/dpi/hs.xsl/26_4251_ENA_HTML.htm</a><br /><br /><span style="color:#000000;">The team is also developing a best practice herbicide guide, using feedback from consultants on what is being used successfully for in-crop and fallow control across the region.<br /><br />If you wish to be part of this short survey, please contact Michael Widderick on</span> <a href="mailto:Michael.widderick@dpi.qld.gov.au">Michael.widderick@dpi.qld.gov.au</a> <span style="color:#000000;">or Steve Walker on</span> <a href="mailto:steve.walker@dpi.qle.gov.au">steve.walker@dpi.qle.gov.au</a> </div></div></div></div></div></div>damsel bughttp://www.blogger.com/profile/04266164657823029589noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-88099182358098043752009-04-28T14:17:00.006+10:002009-05-01T07:57:28.197+10:00New whitefly found!<span style="font-size:180%;"><strong>Detection of Q biotype Bemisia tabaci in Australia<br /></strong></span><br />The presence of Q biotype Bemisia tabaci species complex in Australia has been confirmed by Dr Robin Gunning, NSW DPI. Q biotype was collected from vegetables in the Bowen/Burdekin region during late 2008, as well as from cotton in southern Queensland (Goondiwindi) and north-western NSW (Wee Waa) during 2009. It is likely that Q biotype is more widely distributed than just these regions.<br /><br /><span style="color:#3333ff;"><strong>What are the implications?<br /></strong></span>Overseas studies indicate Q biotype has the capacity to develop resistance to many insecticides including insect growth regulators (IGRs) such as Admiral® and neonicotinoids like Confidor®. High levels of resistance to Admiral® have been detected in horticultural crops in a few locations in north Queensland and some field control problems have been observed for Admiral®.<br /><br />Resistance testing from cotton production areas for the 2008-09 season has not shown any alarming resistance levels to Admiral® to date.<br /><br />Overseas where populations are predominately of Q biotype, moderate to high resistance has developed to Admiral®. Where populations were mostly B biotype, Admiral® has retained high efficacy. This has been the case in Queensland where, according to Dr Gunning, B biotype populations remain susceptible to Admiral® and have a higher susceptibility to neonicotinoid insecticides, compared to Q biotype populations. At this stage Q biotype is showing markedly less resistance to pyrethroids than the B biotype.<br /><br />In Israel, Q biotype has not developed resistance to Pegasus® despite several years of reliance on this product. In horticultural areas, significant resistance to Pegasus® was not found in either biotype.<br /><br /><span style="color:#3333ff;"><strong>Integrated Pest Management</strong></span><br />Practicing good IPM principles can discourage Q biotype numbers from building up. Under natural conditions, B biotype will out-compete Q biotype. However, in an environment of high insecticide use, the more insecticide resistant Q biotype tends to displace B biotype, and once this shift occurs B may not recover to its former levels. Limiting the amount of chemical used against insect pests may favour the dominance of B over Q.<br /><br />Q biotype, like B, has the capacity to vector the virus that causes cotton leaf curl disease. This disease is not present in Australia. The main risk is that any new whitefly incursions, whether Q or B biotype, could carry viruses that are not present in Australia.<br /><br /><br /><p><img id="BLOGGER_PHOTO_ID_5329592974462094530" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 338px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiD4kTTAvxRsI0P48bMqJuikdLhmviBxT0QWxOWoQEn7eez9vEcvduQlED9IT64UIAvFJhVtlLwgv4XeuAqNeE_-yOVm8tw4oxP2ygYBZITCXTP6JTfrZmO5KgLusf_4eNLuAayUZUzIU1H/s400/whitefly+adults.jpg" border="0" /><br /><span style="color:#3333ff;"><strong>Identification</strong></span><br />Q biotype and B biotype can not be distinguished visually. They can only be distinguished by looking at small differences in their DNA or biochemical make-up.<br /><br /><span style="color:#006600;"><strong>WE NEED YOUR HELP</strong></span><br />In order to determine the distribution of Q biotype, we are asking growers and consultants to send in whitefly specimens to the Queensland Primary Industries and Fisheries, Toowoomba. Please refer to details at the bottom of this article.<br /><br /><span style="color:#006600;"><strong>FURTHER READING </strong></span></p><p><span style="color:#000000;">Whiteflies</span> <a href="http://www.dpi.qld.gov.au/cps/rde/dpi/hs.xsl/26_10277_ENA_HTML.htm">http://www.dpi.qld.gov.au/cps/rde/dpi/hs.xsl/26_10277_ENA_HTML.htm</a><br /><br />The Cotton Industry Biosecurity Plan Appendix 3 provides information on Q biotype (page 32) and Cotton Leaf Curl Virus (page 40).<br /><a href="http://www.planthealthaustralia.com.au/project_documents/uploads/Section%209%20Appendix%203%20Pest%20Risk%20Reviews.pdf">http://www.planthealthaustralia.com.au/project_documents/uploads/Section%209%20Appendix%203%20Pest%20Risk%20Reviews.pdf</a><br /><br />Follow this link to the Fact Sheet on Q biotype whitefly. <a href="http://www.dpi.qld.gov.au/cps/rde/dpi/hs.xsl/26_13554_ENA_HTML.htm">http://www.dpi.qld.gov.au/cps/rde/dpi/hs.xsl/26_13554_ENA_HTML.htm</a><br /><br /><span style="color:#006600;"><strong>WHITEFLY SAMPLING</strong></span><br /><span style="color:#cc0000;">Adult whiteflies:</span> In fields where whitefly are present, collect a minimum of 30 adults from random plants throughout the crop. Place these in 65% alcohol (watered down methylated spirits) in a leak proof vial or bottle. Note that >70% alcohol is classified as a dangerous liquid and should not be sent via post or courier.<br /><br /><span style="color:#cc0000;">Immatures:</span> In fields where whitefly are present, collect a minimum of 30 leaves from random plants throughout the crop. Aim to collect leaves that have large immature scales (4th instar/red-eye nymphs) on their underside. Collect only 1 leaf/plant. Pack the leaves into a paper bag and then inside a plastic bag.<br /><br />For live material, send by overnight courier to:<br />Richard Lloyd<br />DEEDI, Primary Industries and Fisheries<br />203 Tor St, Toowoomba Q 4350<br />Ph: (07) 4688 1315<br /><br />Ensure samples are clearly labeled and include the following information:<br />Collectors Name, Phone No., Fax No., Email address<br />Farm Name, Field, Postcode, Region (e.g. Gwydir)<br />Date of Collection, Host Plant (Crop)<br />Comments</p><br /><br /><span style="color:#000099;">Article by Zara Ludgate and David Murray</span>damsel bughttp://www.blogger.com/profile/04266164657823029589noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-36844698465438854212009-03-06T14:22:00.006+10:002009-03-06T14:45:04.889+10:00What is eating my soybean pods?<span style="color:#000099;"><strong>Field crickets</strong><br /></span>High numbers of field crickets have been reported across the Darling Downs in the last couple of weeks, with some large aggregations of adults attracted to lights at night. <em><span style="color:#006600;">Are these crickets doing damage to crops?</span></em> The answer may well be yes.<br /><div><div><div><div><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_OV4y9VHeTOM9OGo4JInOuGQQP8FFcqSLAWc43mVyR_AFXrB_T8DG5V3L8t1ZeLCa-nYsPB9jYb_e_3REfl5wsrgDPHTNuizxVJH7PpZfhSy5UQv0Xzu78NoGFT-ggyJzqUI6b5cSQf44/s1600-h/Black+Field+Crickets+compressed.jpg"><img id="BLOGGER_PHOTO_ID_5309927656630912898" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; WIDTH: 329px; CURSOR: hand; HEIGHT: 195px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_OV4y9VHeTOM9OGo4JInOuGQQP8FFcqSLAWc43mVyR_AFXrB_T8DG5V3L8t1ZeLCa-nYsPB9jYb_e_3REfl5wsrgDPHTNuizxVJH7PpZfhSy5UQv0Xzu78NoGFT-ggyJzqUI6b5cSQf44/s400/Black+Field+Crickets+compressed.jpg" border="0" /></a>Field crickets are generally a pest of pastures but can also attack soybeans, cotton, sugarcane and sunflowers. There are two species commonly found – the brown field cricket and the slightly larger black field cricket. The brown field cricket is the most prevalent at present. Crickets hide during the day in cracking soils or under clods of dirt or crop residue and emerge at night to feed on crops. They usually feed on seedlings but high populations in late summer may feed on more mature plant structures such as sunflower heads and soybean pods.<br /><br /><span style="color:#000099;"><strong>How do I know that crickets are damaging my soybean pods?</strong><br /></span>Crickets are not the only pest of soybean pods. Mice can also do considerable damage to pods, with soybeans often the last of the summer crops to mature and as a consequence the only source of food on offer for mice. </div><div> </div><div>Cricket adults and large nymphs chew into pods to reach the seeds but this damage looks similar to damage done by mice. So how do you determine what pest is doing the damage? </div><br /><img id="BLOGGER_PHOTO_ID_5309930628004784050" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 340px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiHE8HGGePCAsZGezuCHECI8pGBJ1zOgNg2gRtbNcQvwS1wiYRrXOXDYvpPA-mbc3N-1aEvFDwIb3vt_ydGr2b9M41vV7xiheFRTYVMODEXeSo6HGTxRsNbRNKbCu_Wpkd_eLMqx6oCHBg/s400/soypod+damage+crickets.jpg" border="0" />The best time to check for crickets is to inspect crops at dusk or later into the night when crickets are most active. Field cricket activity can also be monitored with light traps. Another way to determine whether crickets are present is by using hessian bags placed out overnight at regular intervals across the paddock. In the morning check for the presence of crickets sheltering under the bags.<br /><br />The best way to determine whether mice are damaging the crop is to go out at night to check for their presence or use mouse bait cards (as described on the DPI&F website).<br /><br />Mice damage to soybeans can be an ongoing and costly problem as soybeans provide good groundcover for mice and excessive grain losses immediately prior to or during the harvesting operation are likely to increase mouse populations given an ongoing food source. This will also impact on early follow-on cereal crops such as wheat and barley.<br /><br />For further information on how to manage mice in your crop please visit the DPI&F website through the link provided below:<br /><br /><a href="http://www.dpi.qld.gov.au/cps/rde/dpi/hs.xsl/4790_8283_ENA_HTML.htm"><span style="color:#cc0000;">http://www.dpi.qld.gov.au/cps/rde/dpi/hs.xsl/4790_8283_ENA_HTML.htm</span></a><br /><br /><span style="color:#000099;"><strong>How do I control the crickets if they are damaging my soybeans?</strong><br /></span>Past experience has shown that foliar insecticide applications do not provide control of crickets. They shelter by day and are found low down under dense canopy at night, making spray contact difficult.<br /><br />Chlorpyrifos-treated cracked grain baits are registered for cricket control in soybeans, but this is mainly used to protect seedling crops. The bait is prepared by mixing 100 mL chlorpyrifos (500 g/L EC formulation) and 125 mL sunflower oil, and adding this to 2.5 kg of cracked wheat or sorghum/ha. The bait is broadcast evenly by air or ground.<br /><br /><span style="color:#3333ff;">Article by David Murray and Kate Charleston</span></div></div></div>damsel bughttp://www.blogger.com/profile/04266164657823029589noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-71241262013113306122009-02-26T11:10:00.007+10:002009-02-26T12:14:13.195+10:00Mirids in MungbeansMirids can cause significant crop losses in mungbeans with yield reductions of up to 25-50% common where high mirid populations (eg 10/m2) are left uncontrolled. Mirids can reduce yields by 60 kg/ha for every mirid/m2 of crop.<br /><br />Mirids can be present in mungbeans at any stage from seedlings to podding. Budding, flowering and early-podding crops are at greatest risk. Low populations of green mirids are often present in vegetative crops but there is no evidence they cause ‘tipping’ of vegetative terminals or have any impact on yield. Mirid populations usually increase with the onset of budding and peak during late podfilll. Generally around 80% of mirids present in flowering/podding crops are nymphs.<br /><br /><span style="font-size:130%;"><strong><span style="color:#000099;">Damage caused by mirids</span></strong><br /></span>Mirids are sucking insects and feed by piercing the plant tissue and releasing a chemical that destroys cells in the feeding zone. This causes plant tissue to discolour and die. Mirids prefer to feed on flowers, buds and young pods, causing these to abort (shed).<br /><div><div><br /><br /><div><br /></div><img id="BLOGGER_PHOTO_ID_5306910823042389922" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 342px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4M17PJ0eeYdkw6SVa8oMMowAxFmpLkBhgM8AwAY-dT438YxyblcpGMIwC7VvoiSg0r_TQbBGqcTUYpNVv59nqC4O9CdJ6QV7PF9ZFqD7GXvjiRmUwX-jLQ6gM7Bh87Yo6J8eR3qnlcNkY/s400/mirid2.jpg" border="0" /><br />Severe mirid damage in mungbean results in fewer harvestable pods being set, however similar symptoms can also be caused by thrips, high temperatures and moisture stress. Mirids may also attack more mature pods, damaging the seeds inside without causing shedding. If pod set is greatly reduced and mirid populations are relatively low (e.g. 0.5 - 1.0 /m2) - loss may be due to other factors.<br /><br />Mungbeans always set many more buds and flowers than they can convert to harvestable pods. Typically (in dryland crops) only 33% of buds/flowers are converted to harvestable pods. This % may be even lower in moisture stressed crops.<br /><br /><div><br /></div>Recent Helicoverpa threshold trials show that mungbeans can compensate for considerable early damage (at budding/flowering) of up to 80% bud loss with no yield loss. However this only occurs when there is adequate moisture and no subsequent pest damage and there will be a delay in crop maturity. . The loss of replacement buds through continuous pest pressure will lead to reduced crop yields.<br /><br />Medium and large mirid nymphs (instars 3-5) are as damaging as adults. Although small mirid nymphs (instars 1-2) are less damaging, they soon develop into larger more damaging pests (within 3-5 days respectively at 300C).<br /><br /><strong><span style="font-size:130%;color:#000099;">Identification of mirids</span><br /></strong>Three mirid species attack mungbeans and include green, brown and (less frequently) crop mirids. All these species are equally damaging. </div><br /><br /><div><img id="BLOGGER_PHOTO_ID_5306923308272109538" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 273px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLFxbSrqyGWwY5zzAaDYckYxz3ggVe9AtUXVFIaAmrWrsEWQ5-OsMRy-1Aa_b8edAp24gR7XVsymXKXEFcqa5aL5EHIHkedwgksq9xQoBRueC0V1Nd-mJZmp6eGGDjES84y0UIqREOMocJ/s400/threes.jpg" border="0" /><br />For more information on the identification of these mirid species please refer to the Integrated Pest Management website by clicking onto the link provided below:<br /><br /><div><a href="http://www.dpi.qld.gov.au/cps/rde/dpi/hs.xsl/26_5085_ENA_HTML.htm"><span style="color:#ff0000;">http://www.dpi.qld.gov.au/cps/rde/dpi/hs.xsl/26_5085_ENA_HTML.htm</span></a></div><br /><p><strong><span style="font-size:130%;color:#000099;">Where do the mirids come from?<br /></span></strong>Mirids move into summer crops when alternative host plants dry off and they seek a fresh food source. Lucerne and sunflowers can be important sources of mirids in mungbean growing areas.<br /><br />Influxes of mirid adults often coincide with northwest winds in spring. There is also evidence of long distance migration, possibly from inland areas, associated with weather fronts. This may be the cause of some of the widespread and repeated influxes of mirids sometimes observed in grain and cotton growing regions early in the summer.<br /><br /><span style="font-size:130%;"><strong><span style="color:#000099;">Monitoring for mirids</span></strong><br /></span>- Mirids are very mobile and in-crop populations can increase rapidly from budding onwards.<br />- Crops should be inspected weekly during the vegetative stage (to pick the start of budding) and twice weekly from budding onwards until post flowering.<br />- In row crops, the preferred method is beat sheeting, as this method is the most effective for helicoverpa and pod-sucking bugs.<br />- Sample 5 one-metre lengths of row (not consecutive) within a 20 m radius, from at least 6 sites throughout a crop.<br />- Avoid sampling during very windy weather as mirids are easily blown off the sheet.<br /><br /><strong><span style="font-size:130%;color:#000099;">Action level</span><br /></strong>Mirid thresholds for budding/flowering mungbeans are 0.3-0.6 per m2 for aerial and ground rig respectively. While mirid thresholds are very low, this is more a reflection of the cheapness of the preferred mirid pesticide – dimethoate ($4/ha + application). The above thresholds are based on the cost of dimethoate. Were indoxacarb to be used, the threshold for an aerial sprayed crop would be 1 mirid/m2.<br /><br />Note that these thresholds are the break even point (cost of control = value of likely damage) and that action only needs to be taken if populations exceed these levels. However in practice, mirid populations usually increase rapidly from budding onwards and spraying at-threshold populations would be justified. Because of the crop’s ability to compensate for early damage, spraying low mirid populations (i.e. at threshold) at very early budding can be delayed slightly with no risk to yield or harvest maturity. Taking this approach reduces the need for a subsequent mirid spray.<br /><br /><strong><span style="font-size:130%;color:#000099;">Cultural control<br /></span></strong>A crop that has a short flowering period reduces the risk of mirid damage. Flowering periods can be shortened by planting on a full moisture profile and by watering crops just before budding. Consider planting crops in at least 50 cm rows (as opposed to broadcast planting) to facilitate easier pest sampling.<br /><br /><strong><span style="color:#000099;"><span style="font-size:130%;">Chemical control</span><br /></span></strong>· Dimethoate at 500 mL/ha (all summer pulses) or<br />· Indoxacarb at 400 mL/ha (mungbeans and soybeans only).<br /><br />Dimethoate is often applied at lower than label rates (eg 200-250 mL/ha). These rates give excellent mirid control but have far less impact on many beneficials. Trail results have shown that the addition of salt (0.5% NaCl) as an adjuvant, improves the effectiveness of dimethoate at lower rates. The amount of salt used (0.5%) has no phytotoxic effect on summer pulse crops. ‘Hard’ water can markedly lower the effectiveness of dimethoate and should be countered by adding a buffering agent such as LI700.<br /><br />Indoxacarb is not recommended at high mirid pressure (>2/m2) because it is less effective than dimethoate. Because it is restricted to one (1) spray application per crop, indoxacarb is best reserved for Helicoverpa control during podding. As mentioned previously, the mirid thresholds are considerably higher if indoxacarb is used.<br /><br /><span style="color:#000099;"><strong><span style="font-size:130%;">Natural enemies</span></strong><br /></span>There are no beneficial species that are recognised to be regulators of mirid populations in mungbeans. However damsel bugs, big-eyed bugs, predatory shield bugs, as well as lynx, night stalker and jumping spiders are known to feed on mirid adults, nymphs and eggs. Naturally occurring fungi (eg Beauvaria) may also infect and kill mirids, but are rarely observed in the field. </p><br /><div><span style="color:#006600;">Article by Kate Charleston and Hugh Brier</span></div></div></div>damsel bughttp://www.blogger.com/profile/04266164657823029589noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-32748840991406823492009-02-20T14:04:00.006+10:002009-05-06T13:54:04.449+10:00Late season pests of pulses and cotton<div><strong><span style="color:#000000;">Go soft early<br /></span></strong><span style="color:#333333;">Go soft early is a basic integrated pest management (IPM) strategy to avoid using non selective pesticides for as long as possible. This approach encourages a build up of predators and parasites to keep early pests in check and buffer the crop against attack later in the season. This strategy is particularly important in soybeans because of the risk of flaring whitefly. With no registered pesticides against whitefly in soybeans the going soft early approach maximises the chances of whitefly parasitism by the recently released wasp Eretmocerus hayati.</span><br /><br /><strong><span style="color:#000000;">Green Vegetable Bugs (GVB) in soybeans</span></strong> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhirP4Lwlofi2ciCa_-3KVXLgnF-xWlzx-R8fZScvHS4bjxF6eAT2xf7FdGD3tj0wWoSp4o9UERC2xyTPYN7fr7r0DlZ6GSvDTC_ZcrwIZbnds6avQiS_4Tl7GqwAax9JZidy8gOmcFjWhB/s1600-h/GVB1.jpg"><img id="BLOGGER_PHOTO_ID_5332553846944725826" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 229px; CURSOR: hand; HEIGHT: 145px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhirP4Lwlofi2ciCa_-3KVXLgnF-xWlzx-R8fZScvHS4bjxF6eAT2xf7FdGD3tj0wWoSp4o9UERC2xyTPYN7fr7r0DlZ6GSvDTC_ZcrwIZbnds6avQiS_4Tl7GqwAax9JZidy8gOmcFjWhB/s400/GVB1.jpg" border="0" /></a><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPdDg8BCJmrJbadYV5EmYLNhFIQXkGydoLhwVwsbhPnqNODN0DHzcotBr3pCi3Twt9zhOUWe3vvxwbEhcp6G76few-wlC1qI319vbrEWGfzjN-Lj5cBBjEa4XhvQ1w52OMECDp41I5LETX/s1600-h/GVB.jpg"></a><br /><span style="color:#333333;">Intervention with non-selective pesticides may be required during pod-fill to control pod-sucking bugs. The most abundant pod sucking bug in soybeans is the green vegetable bug.<br /><br />GVB are often found in the crop prior to pod-fill, but at this stage they are not causing economic damage. By delaying insecticide use untill pod-fill reduces the risk of flaring whitefly, because as pod-fill progresses, the leaves become progressively less attractive to this pest.<br /></span><br /><span style="color:#333333;">GVB is primarily a pod feeder with a preference for pods with well-developed seeds. Summer pulses remain at risk until pods are too hard to damage (very close to harvest). Damaging populations are typically highest in late summer crops during late pod-fill (when nymphs have reached or are near adulthood).<br /><br />While many cultivars can compensate for yield loss caused by moderate bug populations, seed quality is adversely affected, particularly for culinary beans which have very low damage tolerances (a maximum of 2% damaged seed). Bug damaged seeds have increased protein content but a shorter storage life (due to increased rancidity). In soybeans, bug damage also reduces seed oil content.<br /></span><br /><div><br /><br /><div><img id="BLOGGER_PHOTO_ID_5304726950367918722" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 428px; CURSOR: hand; HEIGHT: 214px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2XEDGrlHNKnajokHutHjyymbGSRMEEhYr01UrNn1P_MPITVvGaJoE-T0usV-Dx7PZ7cYn-LwxBQ9-fdAkwb81rxqUWLcdiJ_NMT-DsiwFBt6U2qvdUoW0x2vwhyGvQMtBJrJ51WkNVTkW/s400/blog+threshold+gvb+in+soy.jpg" border="0" /><span style="color:#333333;">The only effective registered pesticides for pod-suckers are non-selective and include deltamethrin (Decis) and trichlorfon (Dipteryx). Of these, deltamethrin is the most effective. Note that dimethoate and methomyl are also registered but were found to be ineffective against pod-sucking bugs. </span></div><br /><div><span style="color:#333333;"><strong><span style="color:#009900;">To mitigate the impact of non-selective insecticides, delay spraying podsuckers until early podfill.</span><br /></strong></span><br /><strong><span style="color:#000000;">Green Vegetable Bugs (GVB) in cotton<br /></span></strong><span style="color:#333333;">Cotton is susceptible to damage from GVB from flowering through until one open boll per metre. Damage symptoms from GVB cannot be distinguished from damage done by mirids which include warty growths and brown staining of lint in developing bolls.<br /><br />Thresholds for GVB in cotton are 1 adult/metre from flowering through to harvest. For insecticide options please refer to the cotton pest management guide which can be found on the Cotton Catchment Communities CRC website</span>. </div><br /><div></div><br /><br /><div><a href="http://www.cottoncrc.org.au/content/Industry/Publications">http://www.cottoncrc.org.au/content/Industry/Publications</a><br /><br /><strong><span style="color:#000000;">Grass blue butterfly<br /></span></strong><span style="color:#333333;">Large populations</span><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgj7UXOdAojJPpg3ChuaWpYF-f8KNkXeSeVVkmTgeX8UQVZfw88weTcPxdy9BTKTrT72T2QtDhv7Nlg6zGsucjkpDnfsfeFMkLDe1qoTQ4kVWuHSxTI7y76iMEzxVwY0RR2xMRiyq7lsPio/s1600-h/LEAF3+grass+blue+larva+&+windowing.jpg"><span style="color:#333333;"><img id="BLOGGER_PHOTO_ID_5304727601722641298" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; WIDTH: 257px; CURSOR: hand; HEIGHT: 161px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgj7UXOdAojJPpg3ChuaWpYF-f8KNkXeSeVVkmTgeX8UQVZfw88weTcPxdy9BTKTrT72T2QtDhv7Nlg6zGsucjkpDnfsfeFMkLDe1qoTQ4kVWuHSxTI7y76iMEzxVwY0RR2xMRiyq7lsPio/s400/LEAF3+grass+blue+larva+%26+windowing.jpg" border="0" /></span></a><span style="color:#333333;"> of grass blue butterfly have been observed in soybeans this season. The green slug-like caterpillars feed mainly on leaves. They may be confused with the larvae of the hoverfly which is a beneficial insect and often found near aphid colonies on which they feed.<br /><br />While control is rarely needed, high numbers can damage terminals resulting in plant branching and pods being set closer to the ground. This can indirectly impact on yield as low-set pods are more difficult to harvest. There are no insecticides registered for this pest specifically but anecdotal evidence (from a leading Goondiwindi grower) suggests they are readily controlled with Bt (Dipel).<br /></span><br /><strong><span style="color:#000000;">Pale cotton stainers</span><br /></strong><span style="color:#333333;">Cotton stainers are occasional pests of cotton that feed on developing and mature cotton seed. While previously controlled by broad spectrum insecticides for other pests in cotton, the reduction in chemical use, especially on Bollgard II®, may lead to increased populations which may need to be managed.<br />For more information about pale cotton stainers click on the link provided below:</span><br /><br /><a href="http://www.cottoncrc.org.au/content/Industry/Publications/Pests_and_Beneficials/Sucking_Pests.aspx">http://www.cottoncrc.org.au/content/Industry/Publications/Pests_and_Beneficials/Sucking_Pests.aspx</a><br /><br /><div><span style="color:#009900;"></span></div><br /><div><span style="color:#009900;"></span></div><br /><div><span style="color:#009900;">Article by Kate Charleston and Hugh Brier</span></div></div></div></div>damsel bughttp://www.blogger.com/profile/04266164657823029589noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-39891043630678922042009-02-13T08:16:00.009+10:002009-02-13T09:36:26.008+10:00Soybean Moth causing major damage in soybeans<span style="color:#333333;">Soybean moth <em>Aproaerema simplexella</em> is a very common pest of soybeans but is usually only present in very low numbers. This season high numbers of moths and caterpillars were found especially in the Wide Bay Burnett region with some fields sustaining extensive damage. Similar leaf miners attack many horticultural crops, but are species other than A. simplexella. Weed hosts of soybean moth include emu foot (Psoralia tenax)<br /></span><br /><span style="color:#000000;"><strong><span style="font-size:130%;">Identification</span><br /></strong><span style="color:#333333;">The soybean moth is a small narrow winged moth, up to 6 mm long. The forewings are dark brown/grey, each with a white bar across them, and pale brown hind wings. In soybean crops with large infestations, moths can be seen flying up from the foliage when disturbed.</span> </span><br /><br /><div><div><img id="BLOGGER_PHOTO_ID_5302039284957563810" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 440px; CURSOR: hand; HEIGHT: 331px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8tq2bPDdxUClx5mhfCUnOZXkXu5dVqt_axmEqCMxl0TPXjFbRZPuDebNo05DQKPlPVfNEIXTEc5KgcsT09lpE7h38FNx593COddWEWgcxaZNqNTv3OE-GWe2DAlSZ7kkZ6VrSfLS0LPnX/s400/soybean+moth.jpg" border="0" /><br /><span style="color:#333333;">Small elongated eggs are laid on both the top and underside of leaves, generally near leaf veins. Larvae of soybean moth are pale green/grey and grow up to 7 mm (in length).<br /><br />Other caterpillars that mine and web soybean leaves include soybean leafminer <em>Lithocolletis aglaozona</em>, a much smaller and less abundant species, and legume webspinner <em>Omiodes diemenalis</em>, common in coastal regions, but which is much larger (up to 15 mm) and is bright green. Legume webspinners also web leaves together, rather than mining leaves (feeding inside them).<br /></span><br /><span style="color:#000000;"><span style="color:#333333;">Similar leaf miners also attack many horticultural crops, but are species other than A. simplexella. Weed hosts of soybean moth include emu foot (<em>Psoralia tenax</em>).<br /></span><br /><span style="font-size:130%;"><strong>Damage</strong> </span></span><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixYrcv14lDnHZ3Hk6n0g9UgrYgc-LyQ-PKPQnCfEJXyslA9Z_dlusnN5oz_gKCSlfa1iicoo7dlx-etlWl2eY7UF-uF70lUGaF43evmkbE0oavdduafb7AKH6gjPPyk-a4Mph0Al97ooGH/s1600-h/soybean+moth+2.jpg"></a><br /><span style="color:#333333;">Larvae initially feed inside leaves (i.e. in leaf mines) and emerge after approximately four days to feed externally, folding and webbing leaves together to form a protective shelter. Infested leaves are often crinkled and pulled together in the middle and this together with webbing of leaf is the most obvious symptom of damage. In low numbers the larvae only cause cosmetic damage. While larvae normally feed on leaves only, extremely high populations will also graze on the surface of pods, after they have denuded the crop of leaves. </span></div><div><span style="color:#333333;"></span></div><img id="BLOGGER_PHOTO_ID_5302057473982121106" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 356px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_g5YtDzRFky1ipkqyK02j8R60eYkbKsaIkJgaQxyvTr9772wTHWnOFuICct_ray2O5cMjMx3_J2SUp86C3orFVsg_bgHOkoVJAo5Ly2DYFTsVPu2VB0epL4j8WC5p4FDh_sUZOkagPgeF/s400/soybean+damage+slide.jpg" border="0" /><span style="color:#333333;">Soybean moth infestations are favoured by hot, dry weather, with crops under severe moisture stress most at risk. Large populations can cause extensive damage by stripping all leaves from crops and so reduce photosynthesis and grain production.</span></div><div><br /><div><span style="color:#000000;"><strong><span style="font-size:130%;">Monitoring and thresholds<br /></span></strong><span style="color:#333333;">Monitor crops regularly for the early warning signs of rare plague events. Look for numerous small, pale patches (leaf-mining) on the leaves and large numbers of soybean moths in the crop or around lights at night.<br /><br />The indicative threshold is based on defoliation, with. 33% pre flowering and 15-20% defoliation during early to mid pod-fill.<br /></span><br /></span><span style="color:#000000;"><strong><span style="font-size:130%;">Control<br /></span></strong></span><span style="color:#333333;">In most years control is not required but large infestations in the Bundaberg region will need chemical control to prevent total crop loss. Check thoroughly before spraying, as larvae may have already pupated (as black pupae within the webbing) or reached full size (7 mm) and stopped feeding.<br /></span><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibRndximBcbUnDyu33N50Ab8UQT86qsaGkMuZbqRNUWngOUktETZBHzSWYznk5mqCOD8JnZpG4Ra7bL0V5sR7N2zjTE6Ui980LMPXHII2oLwEk1DI6MA4sVhAKyVZ4Kbwd9IQmebrPlBU1/s1600-h/temclucha.jpg"><img id="BLOGGER_PHOTO_ID_5302046052582443938" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 211px; CURSOR: hand; HEIGHT: 177px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibRndximBcbUnDyu33N50Ab8UQT86qsaGkMuZbqRNUWngOUktETZBHzSWYznk5mqCOD8JnZpG4Ra7bL0V5sR7N2zjTE6Ui980LMPXHII2oLwEk1DI6MA4sVhAKyVZ4Kbwd9IQmebrPlBU1/s400/temclucha.jpg" border="0" /></a><br /><span style="color:#333333;">There are no specific registrations for the control of soybean moth. However pesticides effective against Helicoverpa (except Helicoverpa virus and Bt), and targeting that pest in soybeans will most likely also give reasonable control of soybean moth. </span></div><br /><div><span style="color:#333333;"></span></div><div><span style="color:#333333;">DPI&F plans to investigate the effectiveness of a number of pesticides registered in soybeans (against other pests,) as part of GRDC-funded pulse IPM research project DAQ00086. The hope is to identify at least a moderately selective pesticide to preserve soybean moth parasites such as Temclucha sp., a small Ichneumonid wasp (8 mm). This species has been observed in very high numbers in some crops infested with soybean moth. </span></div><br /><div></div><br /><div><span style="color:#000099;"></span></div><br /><div><span style="color:#000099;">Article by Kate Charleston and Hugh Brier</span></div></div>damsel bughttp://www.blogger.com/profile/04266164657823029589noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-84929257039943004622009-02-11T15:50:00.004+10:002009-02-16T10:35:31.179+10:00Silverleaf whitefly updateThere are reports of large infestations of silverleaf whitefly (SLW) from the Narrabri/Moree region. Exponential growth in whitefly numbers coupled with honeydew on leaves indicates that the whitefly are probably SLW and not East Australian native Bemisia or Greenhouse whitefly (GHW).<br /><br />It is thought that increased host plant availability from a wet winter/spring, warm conditions and a decline in natural enemies due to the use of broad spectrum insecticides has contributed to the high SLW numbers in this more marginal area of occurrence.<br /><br /><strong><span style="color:#000099;">DPI&F entomologists will be visiting Narrabri on Thursday, 11 February 2009 and Moree on Friday 13 February 2009 where they will meet with growers and consultants and speak about SLW and the management options that are available.</span></strong><br /><br />Cotton fields around St George are at or reaching high densities of SLW. Reports indicate Admiral® has been applied on many fields to suppress SLW populations. Parasitism levels of 50% and 70% were recorded from two fields in the St George area. This should help to keep SLW in check later in the season even if they start to re-infest crops post Admiral® spray.<br /><br />SLW numbers in Biloela and Theodore are reportedly dropping off. This may be in part due to parasitism levels. Recent testing for insecticide resistance in populations of SLW from Biloela and Theodore show no alarming results for Admiral®. These results were expected due to the minimal use of Admiral® in central Queensland this season.<br /><br />GHW are in moderate densities in the Norwin region on the Darling Downs. While GHW will produce honeydew it does not normally cause the same problems as SLW which has a wider host range, higher reproductive rate, develops resistance to insecticides rapidly, and is adapted to high temperatures. Where populations are a mix of SLW and GHW, consider treating as if all are SLW.<br /><br />The report on managing silverleaf whitefly by Richard Sequeira and Tracey Farrell can be accessed through the cotton CRC using the link below: <a href="http://www.cottoncrc.org.au/files/5743fee2-f978-4a79-a9d1-9b1800e899cf/Whitefly_Management[1].pdf">http://www.cottoncrc.org.au/files/5743fee2-f978-4a79-a9d1-9b1800e899cf/Whitefly_Management[1].pdf</a>.<br />This document outlines sampling, thresholds and management options for SLW. Remember only one spray of Admiral® is allowed per season.<br /><br /><span style="color:#000099;"><em>Article by Zara Ludgate</em></span>damsel bughttp://www.blogger.com/profile/04266164657823029589noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-16611471609977178602009-01-30T16:10:00.008+10:002009-01-30T17:05:02.393+10:00Latest helicoverpa thresholds for mungbeansRevised thresholds for helicoverpa in flowering/podding mungbeans are based on a rate of damage of 35 kg/ha per larva per square metre in podding crops. The new thresholds are nearly double the old threshold of 1/m2, and make allowances for variations in control costs and crop value. For a typical scenario with pesticide control (including aerial application) costing $40/ha and an anticipated crop value of $600/t, the new threshold (see chart) is 1.9 larvae/m2.<br /><br /><strong><span style="color:#3333ff;">Helicoverpa threshold table for mungbeans 2008</span></strong><br />Based on data from 2006/07 threshold trial<br /><span style="font-size:85%;color:#006600;">Assumes yield loss of 35kg/ha for every larva/m2. No allowance for larval mortality, but this most likely cancelled out by sampling inefficiency with a beat sheet. Yield loss is probably at the upper end of that likely as the trial showed no yield loss for up to 8 larvae/m2 at flowering. </span><span style="font-size:85%;"><span style="color:#006600;">Very high control costs included in table reflect extremely high application costs in coastal crops.</span> </span><span style="font-size:78%;"><br /></span><span style="font-size:78%;"></span><span style="font-size:78%;"><p><br /></span><span style="font-size:85%;color:#660000;"></span></p><img id="BLOGGER_PHOTO_ID_5296977470274240258" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 194px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjCtFKBNvoyqZIo85m-9HyO7FyYbX5rfJK1G3uh-tokbVwbHmzo9BDKGC9U7ZpHNVkhD53QRHd2obD14oihgcIhv30sHXDnRF2LqQ-1zPqkpP7sJUPPZtYQmKdEFjZhsVCdRDypWLmW91uc/s400/heli+tab1.bmp" border="0" /><br /><p><span style="font-size:85%;color:#660000;">Cross-reference the cost of control versus the crop value to determine the economic threshold (ET). </span></p><p><span style="font-size:85%;color:#660000;">If the cost of control = $35/ha and the crop value =$450/t, the ET = 2.2 </span></p><p><span style="font-size:85%;color:#660000;">If the cost of control = $25/ha and the crop value =$650/t, the ET = 1.1 </span></p><p><span style="font-size:85%;color:#660000;">The lower the cost of control, and the higher the crop value, the lower the threshold. </span></p>Note that the thresholds are at the break even point, where the cost of control = the value of the likely damage, i.e. where the benefit: cost ratio is 1:1, or in other words where there is not net gain if you spray and no net loss if you don’t spray. Hence control is only recommended if the population exceeds the economic threshold, in other words if the benefit:cost (B:C) ratio is greater than 1.<br /><br />While IPM guidelines traditionally recommended a B:C ratio of 2:1, most growers using the control cost scenario (above $40/ha) are unlikely to tolerate another $40 of damage/ha before taking action. Therefore use the above table as follows: Decide how much extra potential damage (in $/ha) you are willing to accept before taking action. For example if you are only willing to accept another $10 of damage/ha before taking action, and control costs and likely crop values are $40/ha and $600/t respectively, then adjust your control costs up to $50/t, and cross reference with the above crop value to give an action threshold of 2.4 larvae/m2.<br /><br />While early reproductive damage at flowering may be totally compensated for, significant early damage can delay harvest maturity, and may reduce ‘commercial harvest yield’, i.e. the yield in crops where desiccants are used to dry out green pods lagging behind the main crop of black pods. For this reason, the threshold is conservatively set from flowering to podfill.<br /><br />Recent data suggest early moderate damage can be totally compensated for with no delay in harvest, in well growing crops with plentiful moisture. In such crops, growers might consider using a helicoverpa NPV product such as VivusMax for low-moderate populations (eg 2/m2) provided they are able to guarantee thorough coverage, include an Aminofeed adjuvant and are targeting small larvae (ideally not greater than 5 mm long).<br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFdLUhFkCZdtiJIJCnpuad_dB24OurJnyjgBIuFxx47NTToNw2sjJvOmRKyRLTaGJp0QCKSKOrT62mWbWluZUEtZarwe7-p4pWfrc5ZfO7q0ggVUlYIS3pMajsrZde6GIdEW0gECmrWDKF/s1600-h/Picture1.jpg"><img id="BLOGGER_PHOTO_ID_5296970034246916594" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 220px; CURSOR: hand; HEIGHT: 156px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFdLUhFkCZdtiJIJCnpuad_dB24OurJnyjgBIuFxx47NTToNw2sjJvOmRKyRLTaGJp0QCKSKOrT62mWbWluZUEtZarwe7-p4pWfrc5ZfO7q0ggVUlYIS3pMajsrZde6GIdEW0gECmrWDKF/s320/Picture1.jpg" border="0" /></a><br />In view of the recent changes to the Helicoverpa threshold in vegetative soybeans, a provisional threshold of 4-5 larvae/m2 has been set for vegetative mungbeans, in lieu of the old 33% defoliation threshold (which still holds for loopers). This is because helicoverpa are also likely to target the mungbean’s auxiliary buds which are the precursors to floral buds.<br /><br />The threshold is set lower than the vegetative soybean threshold because mungbean plants are smaller than soybeans. <strong>Note that this vegetative mungbean threshold is provisional and has to be verified in replicated field trials.<br /></strong><br /><strong><span style="color:#000099;">Helicoverpa and mirids</span><br /></strong>Recently we received a number of reports of flowering mungbean crops with above threshold mirid populations and low numbers of Helicoverpa. In such instances, dimethoate (250 mL/ha) plus NPV can be mixed with no risk of incompatibility. <strong>However it is critical to add a buffer such as LI700 to tank mix water to keep the pH below 7, as both dimethoate and NPV are deactivated in alkaline water (pH >7). </strong><br /><br />Note that dimethoate is recommended at the lower 250mL/ha rate as this has proven efficacy in DPI&F’s trials and has far less impact on beneficials than the full registered rate of 500mL/ha. Preserving as many beneficials as possible will complement NPV’s impact on helicoverpa larvae and will reduce the risk of subsequent sprays to control this pest..<br /><br /><span style="color:#3333ff;">Article by Hugh Brier</span>damsel bughttp://www.blogger.com/profile/04266164657823029589noreply@blogger.com2tag:blogger.com,1999:blog-7115720169493343649.post-68870753825577538332009-01-23T11:17:00.005+10:002009-01-23T11:58:29.294+10:00Silverleaf whitefly in cotton – an updateSilverleaf whitefly (SLW) is a serious pest of cotton. It reduces yield and quality of cotton due to feeding damage and excretion of honey dew. It is a difficult pest to manage due to its ability to rapidly increase in numbers and the development of resistance to many insecticides.<br /><br />Resistance testing for the 2007-08 season indicated no alarming results for Admiral® (pyriproxyfen) or Pegasus® (diafenthiuron) in cotton areas. The IRMS guidelines for Admiral® require that only 1 spray may be applied per season. Apart from the cost involved, more then one Admiral® spray has been shown to increase the development of resistance.<br /><br />As part of the management strategy for whitefly it is important to know what species or biotypes are present as these will significantly impact on the management decision that is required. Refer to past beatsheet articles to read more on identifying the different species and biotypes of whitefly.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-CTjQ_9ZFp9L3B08k61rZuhEAPbKB6Meq4YYzW3sEk3RpHLE0Rs4WRLZZWFM76bdz549s2_sJbKzUbYk5MgFvXj61kiqPHiQcTti6uJGAsUftKxJudvU52cGjvCjDjh0wO7UCiE0_svF2/s1600-h/slw.jpg"><img id="BLOGGER_PHOTO_ID_5294292607807519810" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; WIDTH: 290px; CURSOR: hand; HEIGHT: 198px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-CTjQ_9ZFp9L3B08k61rZuhEAPbKB6Meq4YYzW3sEk3RpHLE0Rs4WRLZZWFM76bdz549s2_sJbKzUbYk5MgFvXj61kiqPHiQcTti6uJGAsUftKxJudvU52cGjvCjDjh0wO7UCiE0_svF2/s400/slw.jpg" border="0" /></a>We are seeing mixed populations of whitefly across Queensland. On the Darling Downs, greenhouse whitefly (GHW) has made up >90% of the population in the Norwin area. A sample from Theodore showed the whitefly population was made up of 70% SLW and 30% GHW.<br /><br />In Emerald, a limited number of Pegasus® sprays have been applied for SLW. Pegasus® is best used for early season suppression of SLW at low insect densities or as a late season knock down to prevent honey dew contamination of open bolls.<br /><br />Very few (if any) Admiral® sprays have been applied so far this season. Admiral® may be applied after 1450 day degrees if SLW numbers reach high densities. Remember that only one Admiral® spray may be applied per season to limit the potential for resistance to develop.<br /><br />An excellent publication has been produced through the Cotton CRC by Richard Sequeira and Tracey Farrell That outlines thresholds and sampling methods for SLW in cotton in more detail (<a href="http://www.cottoncrc.org.au/files/5743fee2-f978-4a79-a9d1-9b1800e899cf/Whitefly_Management.pdf">www.cottoncrc.org.au/files/5743fee2-f978-4a79-a9d1-9b1800e899cf/Whitefly_Management.pdf</a>). This should be referred to when making management decisions for this pest.<br /><br />In Emerald, there were high levels of natural control of whitefly from the parasitic wasps, Eretmocerus hayati and Encarsia formosa. Parasitism levels of 40% and 75% were recorded in two fields in the Emerald Irrigation Area. In a field at Biloela, parasites were so abundant that the tiny wasps were clearly visible walking around on leaves. <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLnWLh_St1cfBm2XUxidtlqJ4rc9JF5TQmUtLaE2qPBxu0eOogoYYAycylCYITVc2VR0JsGTyN1fZKtqUyhklNte-9dwS8Op8SRYclOQDYcLKSGQmnQxDK9OKGtdZGibQy2_VjV_vLFkxM/s1600-h/slw1.jpg"><img id="BLOGGER_PHOTO_ID_5294295778745095090" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 203px; CURSOR: hand; HEIGHT: 130px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLnWLh_St1cfBm2XUxidtlqJ4rc9JF5TQmUtLaE2qPBxu0eOogoYYAycylCYITVc2VR0JsGTyN1fZKtqUyhklNte-9dwS8Op8SRYclOQDYcLKSGQmnQxDK9OKGtdZGibQy2_VjV_vLFkxM/s320/slw1.jpg" border="0" /></a><br /><br />It is likely that the high parasitism levels recorded in Emerald and Biloela are due, in part, to very limited mirid sprays earlier in the season. This has avoided flaring SLW and allowed beneficials to multiply and offer a free service to growers and consultants in controlling whitefly.<br /><br />Whitefly numbers are reportedly building up at St George/Dirranbandi. DPI&F entomologists will be visiting the area next week to collect samples for resistance monitoring and check parasitism levels.<br /><br />While whitefly are definitely starting to make their presence felt in cotton fields across Queensland, their presence does not necessarily warrant action. Monitor fields often as whitefly can build up exponentially, identify what species/biotypes are present, use the available thresholds and avoid flaring whitefly by minimising the use of disruptive insecticides and maintaining beneficials in the system.<br /><br /><span style="color:#000099;">Article by Zara Ludgate</span>damsel bughttp://www.blogger.com/profile/04266164657823029589noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-15558260599098699262009-01-15T11:13:00.008+10:002009-01-15T11:46:26.134+10:00New Helicoverpa thresholds in vegetative soybeans<span style="color:#333333;">The new economic threshold for Helicoverpa in vegetative soybeans is 8 larvae per sqare metre and replaces the old 33% defoliation threshold. The new threshold is based on field trials conducted by John Rogers (formerly with DPI&F at Kingaroy). These field trials show that approximately 7.5 larvae per square metre can be tolerated with no yield loss, but that severe yield losses can occur once this critical population (the inflection point) is exceeded.<br /><br />The new threshold (8 larvae/m2) is based on the maximum number of larvae that can be tolerated before there is an economic reduction in yield. The closeness of the threshold and the inflection point is a measure of the severity of the yield losses that can occur once this critical population is exceeded.<br /><br />Previous thresho</span><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEip8fKN7tmoP6n8ejoz7gO6C_TjQX3w4-w9oZWCoFhwb6ytmrxgH3mexAteO_qFLCnGUyQTwXaNaclgxhjtuj9wyjENEZOLEV-iaD-_-0wxg5ErKry1wz65knBHpQPQvKPRASERAv6IBVN6/s1600-h/H14++Large+dark+heli+armigera.jpg"><span style="color:#333333;"><img id="BLOGGER_PHOTO_ID_5291324122841674898" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; WIDTH: 234px; CURSOR: hand; HEIGHT: 127px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEip8fKN7tmoP6n8ejoz7gO6C_TjQX3w4-w9oZWCoFhwb6ytmrxgH3mexAteO_qFLCnGUyQTwXaNaclgxhjtuj9wyjENEZOLEV-iaD-_-0wxg5ErKry1wz65knBHpQPQvKPRASERAv6IBVN6/s400/H14++Large+dark+heli+armigera.jpg" border="0" /></span></a><span style="color:#333333;">lds were based on the maximum defoliation (33% and widely cited in the scientific literature) that can be tolerated without reducing soybean yield. In John Rogers’ trials, Helicoverpa populations equivalent to the new threshold (8/m2) inflicted significantly less than 33% defoliation. Note that the threshold may be influenced by crop size, with fewer larvae tolerable in very early or very small crops, and more larvae acceptable in larger more vigorous late-vegetative crops.<br /><br />The reason yield loss occurs below 33% defoliation is because of Helicoverpa’s feeding behaviour - they are not called budworms for nothing. As well as feeding on leaves, they also feed on the soybean plant’s vegetative terminals and auxiliary buds, the latter which are the precursors to floral buds.<br /><br />Previous vegetative thresholds allowed for vegetative terminal loss (tipping) with 25% terminal loss the cited critical level above which action was required. The new thresholds are below the old terminal-loss guidelines as populations of 8 larvae/m2 destroyed fewer than 25% of terminals in John Rogers’ trials.<br /><br />The crop’s ability to tolerate 7.5 larvae/m2 during the vegetative stage without yield loss, means that Helicoverpa nucleopolyhedrovirus [NPV] (e.g. VivusMax®) can still be safely used prior to flowering, <strong>provided it targets appropriately small larvae (<</strong><strong>7 mm long).</strong> This is because NPV only has to keep populations below this critical level, rather than achieving ≥90% control that would be required if yield loss commenced as soon as populations exceeded 0/m2.<br /></span><br /><span style="color:#333333;">Immediate intervention with a more robust larvicide may be required against extremely high populations (e.g. > 20/m2). While indoxacarb (Steward®) could be used at this stage, only one application is allowed per field per crop growth cycle, and this product is best saved for later in the season when it is most needed.<br /><br />Until data to the contrary is available, the 33% defoliation vegetative threshold is still valid for </span><br /><span style="color:#333333;">loopers and cluster caterpillars which are primarily foliage rather than bud feeders. However, cluster caterpillars are more likely to attack soybean pods than loopers, but not as savagely as Helicoverpa.<br /><br />John Rogers’ studies illustrate the link between a pest’s feeding behaviour and its impact on crop yield. The studies also highlight the importance of having ‘species specific’ data, and that a ‘one threshold model fits all’ approach is not always appropriate. Further trials are planned to study the feeding behaviour and damage potential of cluster caterpillars and all the major looper species attacking soybeans. However, such detailed research is likely to take at least 3-4 years to complete. <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgw_0M4dkifKlWMx4J_29ACkpvrXAJe2vumnUQEN47Wf-o-mw_N5oUuRRSImkywHPVIby1rHeJc8w2IOBsZ9SbrB2V0R9Mr0WdImGJ3fdEYp-p9E0mKTLZHAejBxaCyBweVU9fVe-WI2aLW/s1600-h/Fig+3+Colour.jpg"><span style="color:#333333;"><img id="BLOGGER_PHOTO_ID_5291323774079274354" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 437px; CURSOR: hand; HEIGHT: 332px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgw_0M4dkifKlWMx4J_29ACkpvrXAJe2vumnUQEN47Wf-o-mw_N5oUuRRSImkywHPVIby1rHeJc8w2IOBsZ9SbrB2V0R9Mr0WdImGJ3fdEYp-p9E0mKTLZHAejBxaCyBweVU9fVe-WI2aLW/s400/Fig+3+Colour.jpg" border="0" /></span></a><br /><br /></span><span style="font-size:85%;color:#3333ff;"></span><br /><span style="font-size:85%;color:#000099;"><em>Helicoverpa damage in soybeans </em></span><br /><span style="font-size:85%;color:#000099;"><em></em></span><br /><span style="font-size:85%;color:#000099;"><em>A- vegetative damage</em></span><br /><span style="font-size:85%;color:#000099;"><em>B - damage to terminals results in</em></span><br /><span style="font-size:85%;color:#000099;"><em>C - reduction in pods and yield</em></span><br /><span style="font-size:85%;color:#3333ff;"></span><br /><span style="font-size:85%;color:#3333ff;"></span><br /><span style="font-size:85%;color:#3333ff;"></span><br /><span style="font-size:85%;color:#3333ff;"></span><br /><span style="font-size:85%;color:#3333ff;"></span><br /><span style="font-size:85%;color:#3333ff;"></span><br /><span style="font-size:85%;color:#3333ff;"></span><br /><span style="font-size:85%;color:#3333ff;"></span><br /><span style="font-size:85%;color:#3333ff;">Article by Hugh Brier (DPI&F Kingaroy), John Rogers (formerly DPI&F Kingaroy and Kate Charleston (DPI&F Toowoomba)</span>damsel bughttp://www.blogger.com/profile/04266164657823029589noreply@blogger.com5tag:blogger.com,1999:blog-7115720169493343649.post-47453144946989249612008-12-19T11:32:00.004+10:002008-12-19T11:57:02.979+10:00Insurance spray for mirids in Bollgard II<span style="color:#000000;">With the Festive Season almost here and an irrigation pending, is there value in applying a spray for mirids for peace of mind? This decision to apply an insurance spray needs to be carefully considered because it has the potential to cost much more in the long run.<br /><br />In order to make this decision, we need to understand the population dynamics of mirids, their damage potential and what is currently happening to the crop.<br /></span><br /><strong><span style="color:#000099;">Where do mirids come from? </span><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEik5hXCiAFQhyj_ZebfcpZIJGqq9CElX-DrPwMzJXZWTOCwQJ1DcAR5u0gX2Jx5zUvqGrLmrk15oZ95lox_baG1SapETUVKsHIIVioSwNmmheVs4TsGgVG4dvUv-YldBq56pQY5Eak7FVTv/s1600-h/Green+mirid+adult.jpg"><span style="color:#000099;"><img id="BLOGGER_PHOTO_ID_5281311433852690338" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 325px; CURSOR: hand; HEIGHT: 183px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEik5hXCiAFQhyj_ZebfcpZIJGqq9CElX-DrPwMzJXZWTOCwQJ1DcAR5u0gX2Jx5zUvqGrLmrk15oZ95lox_baG1SapETUVKsHIIVioSwNmmheVs4TsGgVG4dvUv-YldBq56pQY5Eak7FVTv/s400/Green+mirid+adult.jpg" border="0" /></span></a></strong><strong><br /></strong><span style="color:#000000;">Mirids overwinter as adults on wild hosts. In the spring with rising temperature, mirid populations start to build up on alternative hosts around cotton growing areas. Wet winters usually contribute large reserves of alternative hosts which support mirids. Once these hosts hay off and lose their suitability, the mirids can invade seedling or squaring cotton. Mirids sometimes build up in western Queensland, from where they allegedly move on north-westerly winds and invade cotton areas. Mirid adults also continually move into cotton from surrounding hosts and move out of the cotton to alternative hosts throughout the season.</span><br /><br /><strong><span style="color:#000099;">What is happening this year? </span></strong><strong><span style="color:#000099;"><br /></span></strong><span style="color:#000000;">Although the past winter was relatively wet, mirid numbers have been very low across the cotton growing areas so far this year. The reason for this phenomenon is not well understood. It could be that alternative hosts are still fresh enough to continue to support mirids, or the severe and prolonged winter may have had a detrimental effect on mirid populations.<br /></span><br /><strong><span style="color:#000099;">Do we need to be worried about square loss at this stage? </span></strong><strong><span style="color:#000099;"><br /></span></strong><span style="color:#000000;">If square retention is above 70% and mirid numbers are very low (as is the case for many crops this year), there is no need to be unduly concerned. Squares may be lost for various reasons e.g. insect feeding and physiological reasons. </span><br /><span style="color:#000000;"></span><br /><span style="color:#000000;">If mirid numbers are very low and retention is less than 70%, square loss may be due to reasons other than insect feeding and a spray will not help. Square loss at this stage will be compensated fully provided plants do not further suffer from water or nutrient stress or from any other insects.<br /></span><br /><br /><strong>Figure 1. Compensation for mirid damage at squaring stage </strong><br /><strong><br /><br /></strong><strong></strong><img id="BLOGGER_PHOTO_ID_5281309006561171154" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 232px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjI1FpMy2Tq9EGKNIX8nenNOTvAJNZ2K29t4LWfdBt62S23VsLISu_8jbN3GPkl1y11W5Dd6ysta42Vljij8IiEqEiWqj3IwRrIbuMAwrvzT7G88YoUwCbOoJ_Hpm6tfvZYF2BJF6NY-FY_/s400/mirid+graph.bmp" border="0" /><br /><span style="color:#000000;">Figure 1 shows plant mapping data in Bollgard® II.<br /><br />Observation 1 shows the percentage fruit loss for 3 treatments at the squaring stage while observation 2 shows the same 3 treatments at cut out. The treatments consisted of the following:<br /><br />In treatment 1 (blue) plants were sprayed on a regular basis starting from when 60% of plants had their first flower until cut out. Treatment 2 (red) was not sprayed for mirids at any time during the season. Treatment 3 was sprayed regularly throughout the season to provide total protection against mirids</span>.<br /><p><span style="color:#000000;">In observation 1 – the squaring stage – there is a significant difference between treatment 1 (sprayed from squaring) and treatment 3 (sprayed all season) with 18% fruit loss for treatment 1 and 8% loss in treatment 3.<br /><br />However if we now look at what happened in these treatment at cut out, we find that there is no significant difference between treatment 1 and 3. What this shows is that in this experiment the plants had the ability to make up for the early season fruit loss.<br /></span><br /><strong><span style="color:#000099;">Consequences of unwarranted mirid sprays at this stage</span></strong><br /><span style="color:#000000;">There are several consequences of an insurance spray.<br /><strong>-</strong> It is an unnecessary expense.<br /><strong>-</strong> Disruption of benefcial communities at this early stage could flare secondary pests such as aphids, mites and whitefly.<br /><strong>-</strong> Sprays at this stage, whether high or low rate, will not provide long residual protection. Mirids could move in from alternative hosts at any time, and it is best to save the spray for when it is really warranted.<br /></span><br /><em><span style="color:#3366ff;">Article by Dr Moazzem Khan</span></em></p>damsel bughttp://www.blogger.com/profile/04266164657823029589noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-63115533130951278862008-12-16T08:47:00.012+10:002008-12-16T09:13:32.292+10:00Thresholds and changing sorghum crop valueGrowers and consultants need to revise the thresholds used for important insect pests of grain sorghum such as corn earworm and sorghum midge in light of lower prices currently being offered. <img id="BLOGGER_PHOTO_ID_5280154949529566386" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 315px; CURSOR: hand; HEIGHT: 269px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUV-8MD82DslWWG1zqVv4Y-QtpqM2VoWFeT_Ck8U60O6nqCxrCfzCyUlYAlWhYq8NXi1KXz9OXNFqH4XyXybzqNqTrJ1ItChe6E0TyRNKmkVhQP4HWcgYKaSyDOnOuwiL2TfekBd6bQkAG/s320/Spraying+Sorghum.JPG" border="0" /><br /><br />With new crop grain sorghum prices below $200 per tonne, the break even cost of control means that higher pest numbers (density) are needed before control becomes economic, compared to thresholds used last season when grain values were much higher.<br /><br />The use of a benefit:cost ratio is also an important consideration. The break even point is where the cost of control is equal to the loss caused by the pest. The benefit:cost ratio will vary according to individual preferences, and needs to be factored in to calculations.<br /><br /><strong>Corn earworm</strong><br />One corn earworm larva is estimated to consume 2.4 g of sorghum during its lifetime. The economic threshold (i.e. the number of larvae/head where the cost of control is equal to the value of the grain saved) can be calculated using the formula:<br /><br />No. larvae/head = (C x R) ÷ (V x N x 2.4)<br />where<br />C = cost of control ($/ha)<br />R = row spacing (cm)<br />V = value of crop ($/tonne)<br />N = number of heads/metre of row<br />2.4 = weight of sorghum (grams) lost/larva<br /><br />The value of crop loss caused by corn earworm larvae in grain sorghum, for a range of larval densities and grain prices and based on 10 heads/metre of row on 1 metre row spacing, are presented below.<br /><br /><br /><div><div><img id="BLOGGER_PHOTO_ID_5280154360446653634" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 391px; CURSOR: hand; HEIGHT: 137px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpE0qdBmsPhAg4BNhTnbk87gA3MUS8JeYDogG7Tl6C6D9tApSBqPxBWI_DIRR3TuvisGMtBDsZr8VT58dQPPm3vCeiivL8BShoxJK0ZZCf4PGizNzS6Vu6mYM8E3l7Qr05gc4hrTyeS_aF/s400/Heli+Table.jpg" border="0" />When sorghum is valued at $300/tonne, one larva/head could cause $72 crop loss/ha. If the price drops to $150 per tonne, one larva/head causes just $36 crop loss/ha, or 50% less economic damage. This example demonstrates just how important it is to consider each case on its merits, and in particular to consider the cost of control, as it too can vary widely depending on whether aerial or ground spraying is used.<br /><br /><strong>Sorghum midge</strong><br /></div><div><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-9jdW4vvGaha30jbHTR0f1uiLXAq0cK8CDe-Wz7dNUEvORQDd-bt11JxfCOk8KiWxd3UImb6lsdM04sohWbHukA4s9X5Bdbk2zaJBWNLwqpjzIa3qNSk8uw8dgA6Rxgtk9xA81O0kT06z/s1600-h/sorghum+midge+top+compressed.jpg"><img id="BLOGGER_PHOTO_ID_5280155059378977394" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; WIDTH: 258px; CURSOR: hand; HEIGHT: 145px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-9jdW4vvGaha30jbHTR0f1uiLXAq0cK8CDe-Wz7dNUEvORQDd-bt11JxfCOk8KiWxd3UImb6lsdM04sohWbHukA4s9X5Bdbk2zaJBWNLwqpjzIa3qNSk8uw8dgA6Rxgtk9xA81O0kT06z/s320/sorghum+midge+top+compressed.jpg" border="0" /></a>As with corn earworm, decisions to spray for midge are greatly influenced by crop value and it is possible to calculate theoretical yield loss estimates for a particular crop scenario (see table). These yield loss estimates are based on extensive field trials by DPI&F that determined the average yield loss/midge/day on different rated midge hybrids. For a susceptible hybrid, one midge is estimated to cause 1.4 g yield loss/day. (Photo: D. Ironside)<br /><br />Listed below are estimates of midge damage at different grain prices without chemical treatment. </div><img id="BLOGGER_PHOTO_ID_5280158772526734546" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 198px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3kqqgxjHL8fRtk8WyfC9k25n-veOCOKfoa0a7op9F0iuVbXSdcm75ORc7TIOA3Yco30y9eFiZBZkxUoAp4m_L9PitHTV0QCNzijxlunnTvQDo5recioC_nzUaN5aXhM16NR5qXHy8yyKn/s400/Midge+Table.jpg" border="0" />The yield loss estimates in the table assume that spraying results in a 100% kill and that there is no midge damage prior to chemical application. It also assumes that the same average midge pressure persists over 4-5 days. In reality research has shown that one well timed insecticide for midge (put on from panicle emergence and before midge even enter the crop) will still only prevent 70-80% damage protection in lower rated sorghum hybrids. In 8+ rated hybrids, yield losses can be reduced by over 90% with this spray timing.<br /><br />If the total cost of applying a synthetic pyrethroid by plane is around $20/ha, we can see that at a grain price of $150 per tonne, it is simply not economic to spray mid to high rated hybrids at 1 midge/head and 8+ hybrids at 3 midge/head. It should be emphasised that 8+ is the highest rating that can be assigned to midge resistant hybrids. There are some 8+ lines that would have a considerably higher rating if the scale was extended, and are practically immune to midge damage.<br /><br />The above information shows the importance of calculating thresholds for the current situation, rather than relying on a fixed value from one year to the next.</div>BigBughttp://www.blogger.com/profile/11764696091701617022noreply@blogger.com2tag:blogger.com,1999:blog-7115720169493343649.post-35173633980119815522008-11-26T11:33:00.016+10:002008-11-26T14:35:52.148+10:00Bring on NPV against grubs on grain sorghum<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifSFZKyh7Vq1ram5Gu8ePnJILeS0yWIUum8V164Bg2e6j7O5YCJKdslBUIri31lj6t-IABhtie7A7eWKS_gehoKYl0TPAhKQd0LGIeooCdtGK9tkF3-AgYJEd4Z2vJIGSt0k1bh7oGGr8c/s1600-h/Brown+anthers.jpg"><img id="BLOGGER_PHOTO_ID_5272777467923461522" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 218px; CURSOR: hand; HEIGHT: 323px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifSFZKyh7Vq1ram5Gu8ePnJILeS0yWIUum8V164Bg2e6j7O5YCJKdslBUIri31lj6t-IABhtie7A7eWKS_gehoKYl0TPAhKQd0LGIeooCdtGK9tkF3-AgYJEd4Z2vJIGSt0k1bh7oGGr8c/s400/Brown+anthers.jpg" border="0" /></a> Every year caterpillars of the corn earworm (helicoverpa), <em>Helicoverpa armigera</em>, cause losses to sorghum crops. Regular inspection during flowering is important to detect caterpillar infestations and properly time control measures.<br /><br />Pre-flowering heads of grain sorghum are very attractive to egg-laying moths of the corn earworm. On any individual head, most eggs are laid prior to the start of flowering, as indicated by the presence of yellow anthers.<br /><br />By the end of flowering, when brown anthers are present at the base of the head, eggs will have hatched and most larvae will be less than 7 mm in length.<br /><br />A timely spray application of the naturally occurring biopesticide NPV (nucleopolyhedrovirus) remains the best control option for grain sorghum crops under attack from corn earworm.<br /><br /><br />NPV performs exceptionally well on grain sorghum, with well timed sprays usually achieving greater than 90 per cent control while leaving beneficial parasites and predators to mop up survivors.<br /><br />If the spread of flowering in a crop is large, it may be better to spray earlier rather than wait until 50% of the crop is at the brown anther stage. This is because caterpillars on the earliest flowering heads may be larger than the ideal size to target with NPV, and they will cause some damage if not adequately controlled with NPV.<br /><br />Research has shown that early application of NPV creates a disease outbreak and secondary NPV infection will control most caterpillars on late flowering heads.<br /><br />Other issues to ensure good results with NPV<br /><br /><strong>Water quality<br /></strong>Water used in spray mixes should have a pH of 7. Alkaline water will seriously reduce the performance of NPV, so buffer water with Li700 or equivalent to neutralise pH.<br /><br /><br /><strong>Water volumes</strong><br />For high-volume, water-based sprays, a minimum of 30 L water/ha is recommended for aerial application, and 100 L water/ha for ground rig application.<br /><br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUEueJz2ZwGXe19hvgEsY2oSoG0CC2w_nAq9fIbrOmm1hSkQ8PfwdyaYd2GThKp8UoGx8uAeJJlDV1-zW7SLOrcxLg7D9DZB_Dtsi61RjsbhnbUYXGkLTD7vZNo2AGKnxMvB7p1BVBqT_h/s1600-h/NPV2+Sorghum+Dec2007+007.jpg"><img id="BLOGGER_PHOTO_ID_5272779031483746354" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; WIDTH: 265px; CURSOR: hand; HEIGHT: 210px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUEueJz2ZwGXe19hvgEsY2oSoG0CC2w_nAq9fIbrOmm1hSkQ8PfwdyaYd2GThKp8UoGx8uAeJJlDV1-zW7SLOrcxLg7D9DZB_Dtsi61RjsbhnbUYXGkLTD7vZNo2AGKnxMvB7p1BVBqT_h/s400/NPV2+Sorghum+Dec2007+007.jpg" border="0" /></a><strong>Coverage<br /></strong>NPV must be ingested to be effective, so the challenge is to achieve good coverage of the target. This means paying particular attention to water volumes, nozzles, operating pressure, weather conditions, etc. You want to spread NPV over as much of the head as possible to ensure caterpillars have a high chance of picking up a lethal dose as they feed on the head.<br /><br /><strong>Additives<br /></strong>Additives such as Amino Feed, etc. are not recommended when NPV is applied to grain sorghum.<br /><br />Paying attention to the detail will ensure the best results from NPV.<br /><br /><em><span style="color:#3333ff;">Article by Dr. Dave Murray</span></em><br /><br /><br /><span style="font-size:130%;"><strong>New Beat Sheet contributors</strong><br /></span><br />The beat sheet blog team has been expanded and includes two new contributors, Kate Charleston and Zara Ludgate.<br /><br /><strong>Kate</strong> is the development extension officer with the entomology team in Toowoomba. Her role is to provide information about IPM in field crops as well as training to growers and industry in managing insect pests according to IPM principles.<br /><br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3q3DPYSjMQkQdeYCtN9esqgFuGK6yAv_2a0EXGOgioyL9qboiijYbQyJGT9UjSOMMu-dINMQxFLd8GdicvNhI8BMJ1tOULWAXXJP2xhIa1XfJ7oilBfNuUOK_iB59G2k52ppZ7C-UA9pI/s1600-h/kate-faded-bg.jpg"><img id="BLOGGER_PHOTO_ID_5272784249664387250" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; WIDTH: 126px; CURSOR: hand; HEIGHT: 140px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3q3DPYSjMQkQdeYCtN9esqgFuGK6yAv_2a0EXGOgioyL9qboiijYbQyJGT9UjSOMMu-dINMQxFLd8GdicvNhI8BMJ1tOULWAXXJP2xhIa1XfJ7oilBfNuUOK_iB59G2k52ppZ7C-UA9pI/s400/kate-faded-bg.jpg" border="0" /></a>Kate joined entomology in June 2008 and has previously worked as a research scientist, agronomist, plant health inspector and extension officer. She started her career with the Department of Primary Industries in Tasmania and joined the Queensland Government in 1999 as an extension officer in a sugar project at South Johnstone in Far North Queensland. Kate has worked with sugarcane, cotton and pulse crops and has considerable training and extension experience.<br /><br /><br /><br /><br /><strong></strong><br /><br /><strong>Zara</strong> has just started her career in entomology research. She comes from a rural background and completed a degree in plant and soil science at St Lucia, Brisbane in 2007. For her honours year she investigated the effect of a plant defence compound on the fitness of diamondback moth.<br /><br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTKdSjX8uhlEML-9HA7mb6rcspyMBzjJ69r9-1hHhjdw1f8WCHQp4681Mg5up615Z5LZuWXFFjL1KtUXiig-S51HnG_Sj92dZ5YrX6WNLaHl23nKnWBpYCRgcscp-fQ83xCTJsmwPiTNyo/s1600-h/Zara+Ludgate+Mar08.jpg"><img id="BLOGGER_PHOTO_ID_5272797146400923906" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 111px; CURSOR: hand; HEIGHT: 137px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTKdSjX8uhlEML-9HA7mb6rcspyMBzjJ69r9-1hHhjdw1f8WCHQp4681Mg5up615Z5LZuWXFFjL1KtUXiig-S51HnG_Sj92dZ5YrX6WNLaHl23nKnWBpYCRgcscp-fQ83xCTJsmwPiTNyo/s400/Zara+Ludgate+Mar08.jpg" border="0" /></a>While in Brisbane she provided technical support for research into bio-pesticide production for helicoverpa and green vegetable bug management. She is now based in Toowoomba with the crop protection systems - entomology unit. Her current research interests include insecticide resistance in whitefly and integrated pest management in grain crops.damsel bughttp://www.blogger.com/profile/04266164657823029589noreply@blogger.com2tag:blogger.com,1999:blog-7115720169493343649.post-46044221539330187462008-11-05T12:28:00.013+10:002008-11-05T13:04:00.665+10:00Managing Helicoverpa larvae in chickpea crops close to dessication and harvest.<div align="justify"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxlerBmFt9cdOro32OEz-GcDuEsnrUNgGH9FXGhtAWIoSvz0_xGgfL05T1ttSdt745ZCDkEEWmBf3iLX04yoVz7HFzC-OECsSri0Z-YCyvHjfw-QcjcCdYad8CvPCf7LAToN_8sT6_Gt0/s1600-h/Conroy+C.JPG"><img id="BLOGGER_PHOTO_ID_5265000778752189010" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 300px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxlerBmFt9cdOro32OEz-GcDuEsnrUNgGH9FXGhtAWIoSvz0_xGgfL05T1ttSdt745ZCDkEEWmBf3iLX04yoVz7HFzC-OECsSri0Z-YCyvHjfw-QcjcCdYad8CvPCf7LAToN_8sT6_Gt0/s400/Conroy+C.JPG" border="0" /></a> Over the last week or so we have received a number of enquiries about how best to manage new egg-lays, and populations of small larvae, in chickpea crops that are close to dessication and senescing.<br /><br />Of most concern are crops that still have reasonable areas of green crop in them, and what the likelihood of damage is if the weather is cool and moist rather than hot and dry.<br /></div><div align="justify">Hot, dry weather will rapidly advance a chickpea crop which means that very small and small larvae are unlikely to survive on leaves of rapidly deteriorating quality. As the pods dry they also become more resistant to damage by small to medium larvae. In summary, this means that the major source of damage in a scenesing crop is late medium and large larvae. </div><div align="justify"><br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgXrzlxqLY0m94X4TjKjEqpYd9D0dJDKfT8bXFEuLme1JwezoSCM85E8IWWk6oxQBJ4NqMz8jgb3nSCJCN1nCAc_Pdv0lSwDKUJ4PU1sqUsjSqYaWTfApy8yMIR690GrayIh3m91QwaK1I/s1600-h/Conroy+E.JPG"><img id="BLOGGER_PHOTO_ID_5264998686703871570" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; WIDTH: 400px; CURSOR: hand; HEIGHT: 300px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgXrzlxqLY0m94X4TjKjEqpYd9D0dJDKfT8bXFEuLme1JwezoSCM85E8IWWk6oxQBJ4NqMz8jgb3nSCJCN1nCAc_Pdv0lSwDKUJ4PU1sqUsjSqYaWTfApy8yMIR690GrayIh3m91QwaK1I/s400/Conroy+E.JPG" border="0" /></a>Therefore, the recommended approach to managing <em>Helicoverpa</em> populations in the later stages of a chickpea crop is to continue to monitor both number and size of larvae. If the population of medium and large larvae exceeds the economic threshold, AND the crop is still susceptible then treatment may be warranted.<br /><br />The table below gives an indication of how rapidly <em>Helicoverpa</em> larvae will develop at this time of year.<br /><br /></div><div align="justify"></div><div align="justify"></div><div align="justify"><br /></div><div align="justify"><strong></strong></div><div align="justify"><strong></strong></div><div align="justify"><strong></strong></div><div align="justify"><strong></strong></div><div align="justify"><strong></strong></div><div align="justify"><strong></strong></div><div align="justify"><strong></strong></div><div align="justify"><strong></strong> </div><div align="justify"><strong></strong> </div><div align="justify"><strong></strong> </div><div align="justify"><strong>Predicted development times for <em>Helicoverpa</em> larvae (Oct-Nov 2008) - Dalby<br /></strong>Up to 3 November the prediction uses 2008 temperatures for Dalby. Beyond 3 November, the predictions use long term average temperatures (long term averages are generally cooler and development slower).<br /><br /></div><img id="BLOGGER_PHOTO_ID_5265000323898173074" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 345px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1tbVUJxaQqNaIer-zRRNvKWkAMrgw4xWmESCua4LZFNgphyVuo9DFrxiWuKDyJ-Bq18Hgx9H0KEiAhIf53GNnou23boKff4tlmyrKbnxGk5Z6eX-KjJT27fnS9xvt8A6oF4MEtJPwVLI/s400/Heli_devel_Nov5_08.jpg" border="0" /> <p align="justify">The predictions indicate that larvae are developing from very small to medium in around 7 days and from small to medium in 3 days.<br /><br />At this stage of the crop, a wait and see approach (continue checking the crop 1-2 times a week) to is recommended principally because it is difficult to predict a week or two ahead how fast a crop will dry down, and what the <em>Helicoverpa</em> population will be whilst the crop is still susceptible. The alternative approach is to treat above threshold populations of small larvae when they are detected. This approach is likely to result in treatment of fields that subsequently would not have been at risk of damage, particularly if the crop dries faster, or larval mortality is higher than expected.<br /><br />The options available for the treatment of <em>Helicoverpa</em> infestations late are limited because of withholding periods (WHP). Methomyl has a 1 day WHP while thiodicarb has a 21 day WHP. Indoxacarb (Steward<span style="font-size:78%;">TM</span>) has a 21 day WHP, but no more than one application is permitted per crop growth cycle, and the cut-off for indoxacarb use has now passed in all regions (15 Sep in CQ, 15 Oct in warm areas, 30 Oct in cool areas). Check with others in your local area on their experience with the efficacy of options when making a choice.</p><p align="center"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgVT0AQn5WzoFK0Zbic-8UBkX6v_KLLZrhSHst2cLwfu-sP6zzmQ4k1itv-DO_WkgStj4F1yM4Q2Goz-pILWbTwWWeN2V2JWnbIeYcoCZNRTlECmK-rM92LfxwV1UjEcTvCti-l9JKom8/s1600-h/Chickpea+harvest+C.JPG"><img id="BLOGGER_PHOTO_ID_5264998694273746530" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; WIDTH: 400px; CURSOR: hand; HEIGHT: 300px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgVT0AQn5WzoFK0Zbic-8UBkX6v_KLLZrhSHst2cLwfu-sP6zzmQ4k1itv-DO_WkgStj4F1yM4Q2Goz-pILWbTwWWeN2V2JWnbIeYcoCZNRTlECmK-rM92LfxwV1UjEcTvCti-l9JKom8/s400/Chickpea+harvest+C.JPG" border="0" /></a></p>bugladyhttp://www.blogger.com/profile/13351824435251392456noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-52184646099346851822008-10-20T10:59:00.011+10:002008-10-20T11:41:53.499+10:00Armyworm in wheat<div align="left">Over the past couple of weeks there have been numerous reports of armyworm in both barley and wheat. The appearance of armyworm in wheat raises a number of questions:<br />1) Do they behave the same way in wheat as in barley in relation to the type of damage they cause<br />2) what is their damage potential and is there an economic threshold?<br />3) What sort of strategy can be used to monitor and manage populations?<br /><br />For information on armyworm identification see previous Beatsheet postings on armyworms.<br /><a href="http://thebeatsheet-ipmnews.blogspot.com/2007/10/can-you-confidently-identify-armyworm.html">http://thebeatsheet-ipmnews.blogspot.com/2007/10/can-you-confidently-identify-armyworm.html</a><br /><br /><a href="http://thebeatsheet-ipmnews.blogspot.com/2007/09/watch-for-armyworms-in-barley-and-oats.html">http://thebeatsheet-ipmnews.blogspot.com/2007/09/watch-for-armyworms-in-barley-and-oats.html</a><br /><br />There is no reason to expect armyworm to behave differently in wheat to barley. This means you can expect to see feeding on leaves whilst the crop is still green, and then on stems as the crop dries down further.<br /><br /><span style="font-size:130%;"><strong>Characteristic armyworm damage in winter cereals</strong></span><br />During the vegetative growth phase, plants can tolerate considerable leaf feeding. Leaves may look tattered from the eaten-out leaf margins. Faecal pellets around the base of plants are another indication of armyworm infestation. Armyworm generally do not require control during the vegetative stage. </div><div align="center"><br /></div><div align="center"></div><div align="center"><br /></div><div align="center"></div><img id="BLOGGER_PHOTO_ID_5259040284833916370" style="DISPLAY: block; MARGIN: 0px auto 10px; CURSOR: hand; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgzjZG3840CbrK39nuEQMD40cxiYGn7f_SYxk5g_hYTvnQMeLpJFOIvHiLxWOQa0pvJn0A8Urf9XXsFFsvTlr19fGayGP3EJNBHxo5zSwu6a7luxlYtppEn_SWpfgov_n-neCCFfPHW44/s400/armyworm_veg+damage_Crooble_08.jpg" border="0" /> <p align="center"> <span style="font-size:85%;"><strong><span style="color:#3333ff;">Ragged flag and other leaves on a maturing barley crop</span></strong> </span><br /><br /></p><div align="center"></div><br /><br /><p align="left">The most serious armyworm damage in cereal crops occurs when larvae feed on the upper flag leaf and stem node as the crop matures. Larvae target the stem node as the leaves become dry and unpalatable, and the stem is often the last part of the plant to dry. Head cutting begins at this time. <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLmpgRKes7yJ1sQRdyyL1cWny9ITZvC10BZ3Ore2wdCy6vZ17jqsba1QxGOt3ycLPx997adjjdON63YBn7ENtPeZ6VKqNmO_4Ub_l2S_a5kwm7Q9-r9RT0MyK28HtKRdK7DaFPK-E6d9kP/s1600-h/armyworm+headcutting.JPG"></a></p><div align="left"><span style="font-size:85%;"></span></div><div align="left"></div><div align="left">One large larva can sever up to seven heads of barley a day. One larva a square metre can cause a loss of 70 kg/ha grain per day. A larva takes around 8-10 days to develop through the final, most damaging instars, so the crop is susceptible to maximum damage for this period.<br /></div><strong><span style="font-size:85%;color:#3333ff;"></span></strong><br /><strong><span style="font-size:85%;color:#3333ff;"></span></strong><br /><img id="BLOGGER_PHOTO_ID_5259044538795119090" style="DISPLAY: block; MARGIN: 0px auto 10px; CURSOR: hand; TEXT-ALIGN: center" height="342" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjWc55IQk3k6Tu-PTnYEvjPD8WDks1Qm58uTiux6q2Y3zABErPb9Zf-hiSLQxwDcfqEsv7RlnWE1gGZpR6V2tirmLuXm-tu5GH7GgZcmRi1JBTKIR-QMmncQA6gNpRtpwgazMBuWw0fGCc/s400/armyworm_head_cutting_copy.jpg" width="207" border="0" /><strong><span style="font-size:85%;color:#3333ff;">Head cutting in barley caused by armyworm</span></strong><br /><br /><strong><span style="font-size:130%;">Calculating an economic threshold</span></strong><br />The following table shows the value of yield loss incurred by 1 larva/square m per day, based on approximate current values for wheat and an estimated loss of 70 kg/ha per larva.<br /><br /><img id="BLOGGER_PHOTO_ID_5259035036420855186" style="DISPLAY: block; MARGIN: 0px auto 10px; CURSOR: hand; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiAIY_wGWtSNZQpZRFwcvj0adE9-o_obGpMjsF-KuWmg8K47xbGJR_wO0EbW0LJs2-JeGxUxazt_K9JhSyr3ZB6v0FuJhQn_OgCX6yV1NjRXIouf4pFSfFsX4zCgF6tF_keRJymmGccmP0/s400/Armyworm+in+wheat_Oct08_MM_table.jpg" border="0" /> Based on these figures, and the relatively low cost of controlling armyworm, populations in ripening crops in excess of 1 large larva per square metre will warrant spraying.<br /><br /><span style="font-size:130%;"><strong>Monitoring and management strategy</strong></span><br />For insecticide application to be economic, check or scout the crop and assess the problem before head cutting starts. Check for larvae on the plant and in the soil litter under the plant. Late in the day, when the larvae are becoming active, use a sweep net (or swing a bucket through the crop) to make a quick assessment of whether armyworm larvae are present in the crop. Infestations are often patchy, so check a number of sites across the field.<br /><br />Some judgements will need to be made about how quickly the larvae will reach damaging size and when this will occur in relation to the crop's development.For example, if the crop is nearing full maturity/harvest, and the grubs are still small, then there is most likely no need to spray. Small larvae take 8-10 days to reach a size capable of head lopping.The other extreme would be a late crop that is still very green and at early seed fill. In this case, any small larvae present will most likely reach their most damaging size in time to significantly reduce crop yield, and so a spray is more likely to be required.<br /><br />I you are unable to monitor the crop on a regular (daily) schedule during the critical period of drying down, and armyworm are present, it may be better to spray just in case. This is not the preferred option, but provides peace of mind in a year like this where armyworm are abundant.<br /><br /><strong><span style="font-size:130%;">Early recognition</span></strong><br />It is essential to recognise the problem early and be prepared to spray when economic damage is imminent. A cereal crop can be almost destroyed by armyworm in just a few days. Whilst large larvae do the head lopping, controlling smaller larvae that are still leaf feeding may be more achievable.<br /><br /><strong><span style="font-size:130%;">Control</span></strong><br />Many chemicals will control armyworms. However their effectiveness is often dependent on good penetration into the crop to get contact with the caterpillars. Control may be more difficult in high-yielding thick canopy crops, particularly when larvae are resting under leaf litter at the base of plants. As larvae are most active at night, spraying in the afternoon or evening may produce the best results.<br /><br /><br />If applying sprays close to harvest, be aware of relevant Withholding Periods. Always read the label.<br /><br /><br />Biological control agents may be important in some years. These include parasitic flies and wasps, predatory beetles and diseases.bugladyhttp://www.blogger.com/profile/13351824435251392456noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-38027378956427701612008-10-08T14:14:00.019+10:002008-10-14T14:10:52.514+10:00Helicoverpa management in chickpea – a refresher<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjK1K4kI_idY266A_JnQOnO5a_keDFWe8hhDE1f9fqkvE8_F8-lBQ8dqi3WBi61QS_Nx30xHNKdc7dhnzZ7EalXHGroY-9pMQIPgSAQolRTfshUE5r-CjGvCqZu_kjPWg2E3D2Xfl2E3Ouv/s1600-h/CP_brochure_pics_1.jpg"><img id="BLOGGER_PHOTO_ID_5254998188540677474" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; CURSOR: hand" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjK1K4kI_idY266A_JnQOnO5a_keDFWe8hhDE1f9fqkvE8_F8-lBQ8dqi3WBi61QS_Nx30xHNKdc7dhnzZ7EalXHGroY-9pMQIPgSAQolRTfshUE5r-CjGvCqZu_kjPWg2E3D2Xfl2E3Ouv/s400/CP_brochure_pics_1.jpg" border="0" /></a><br /><div></div><div>A comprehensive overview of <em>Helicoverpa</em> management in chickpea can be found in the DPI&F brochure <strong><em>Helicoverpa</em> management in chickpea</strong> (2007). You can read or download a copy of the brochure at the DPI & F website at <a href="http://www.dpi.qld.gov.au/fieldcrops">www.dpi.qld.gov.au/fieldcrops</a>. Click on the link to <strong><em>Helicoverpa</em> management in chickpea</strong> where you will find the brochure. </div><br /><div><div><div><div><div><div><div><span style="font-size:130%;"><strong>Key management decisions</strong><br /></span>The following is an excerpt from the Helicoverpa management in chickpea brochure, and deals specificially with determining whether an infestation of helicoverpa warrants control – based on the economics of potential yield loss vs cost of control.</div><br /><img id="BLOGGER_PHOTO_ID_5254647470132570434" style="DISPLAY: block; MARGIN: 0px auto 10px; CURSOR: hand; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZAYY7xm09wi9F7fkffaj-isX3sq-5LISgh6mQ7wvzePnQrotjlm0_rcKE9fLzRTTjfdhUWyzC-vjDq-MoyWeLCu6Y1g234-pbvOUmmCvUmzwyORUWuIYRwEYsGK3w9NiWZS6gP2BSWbE/s400/CP_brochure_ET_1.jpg" border="0" /> <img id="BLOGGER_PHOTO_ID_5254648246851504018" style="DISPLAY: block; MARGIN: 0px auto 10px; CURSOR: hand; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRv0RxSLU0HA6dOSPB3c0n2Ld2I9nJMSxyuMYGc3lprA2-p7KoMya6cemPHu1Bga2YLJVz7zDD8_grMIVhjB4aaJkbYngVZriLDfJNA8VkkKfoL3sRis7jefni2PMHHEv592ZcbqYZzQQ/s400/CP_brochure_ET_2.jpg" border="0" /><br /><img id="BLOGGER_PHOTO_ID_5254647474577046770" style="DISPLAY: block; MARGIN: 0px auto 10px; CURSOR: hand; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTyQU3uLuTdKZqfzIwwWNxC9qu0FLWAswr88QJOByUUk4BWGG5tS8aFgD7ta_xcX3gYPxuO7nVUYTjXan6E5e-RURyn2PkvtwXNV7N8hXGfFLppwBky_tywrcFIOy3gx92Kwmd-vy-xzA/s400/CP_brochure_ET_3.jpg" border="0" /><br /><br /><br /><div><strong><span style="font-size:130%;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjO5FBp2LPU-XqO3Fxct5LILFb_HWMSM5sd7mbuiuPsnjQ4oG9bHVrZqQAVvC7YOxKjxtyab12PF69zkQlvybwXUjUmBHOjn7fLTjBTag2VyxFht8YXOFlVWN9htxNJ9CEdQDW2_RxZcsU/s1600-h/CP_brochure_pics_2.jpg"><img id="BLOGGER_PHOTO_ID_5254648571081843730" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; CURSOR: hand" height="427" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjO5FBp2LPU-XqO3Fxct5LILFb_HWMSM5sd7mbuiuPsnjQ4oG9bHVrZqQAVvC7YOxKjxtyab12PF69zkQlvybwXUjUmBHOjn7fLTjBTag2VyxFht8YXOFlVWN9htxNJ9CEdQDW2_RxZcsU/s400/CP_brochure_pics_2.jpg" width="162" border="0" /></a>If control is warranted, which product?<br /></span></strong>There is a range of products registered for helicoverpa control in chickpea. However, the use of synthetic pyrethroids is really only an option in regions where <em>H. punctigera</em> dominates, or where the population is predominantly made up of larvae smaller than 5 mm in length. The use of SPs against a predominantly <em>H. armigera</em> population is likely to deliver a poor result in terms of control. </div><br /><br /><div>NPV (VivusMax) and Bt (e.g. Dipel) are two options which are effective against both species of <em>Helicoverpa</em>. They are most efficacious when deployed to control populations of small larvae (less than 7 mm in length), and lower pressure infestations.</div><br /><br /><div></div><div>Thiodicarb (Larvin) is another option, particularly where efficacy of this product in the local area is known to be high. Methomyl (Marlin®) could be considered whare large larvae are present close to harvest as it has a 1 day withholding period</div><br /><br /><div>Spinosad (Tracer II ™) and indoxacarb (Steward ™) are both effective against both <em>H. armigera</em> and <em>H. punctigera</em>. Remember that Steward has a cut-off for use in chickpea (15 September in CQ, 15 October in warm areas, 30 October in cool areas). </div><br /><br /><div>One strategy for the management of mixed age populations of helicoverpa is to use Steward™ first, if prior to cut-off, and then one of the other products if the crop needs to be sprayed again. </div><br /><br /><br /><br /><div></div></div></div></div></div></div></div>bugladyhttp://www.blogger.com/profile/13351824435251392456noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-20864323121649784502008-10-01T14:45:00.005+10:002008-10-01T15:02:04.685+10:00What are those grubs in winter cereals?Grubs in winter cereals are not unusual at this time of year, and already there have been reports of high numbers (up to 20/m2) in Central Queensland wheat (Figure 1). More grubs can be expected in southern districts as the season warms up.<br /><br />The two most likely larvae (grubs) found in winter cereals are the corn earworm, <em>Helicoverpa armigera</em>, and the common armyworm, <em>Leucania convecta</em>. See previous blog postings for more information on these pests.<br /><a href="http://thebeatsheet-ipmnews.blogspot.com/2007/10/can-you-confidently-identify-armyworm.html">http://thebeatsheet-ipmnews.blogspot.com/2007/10/can-you-confidently-identify-armyworm.html</a><br /><br /><br /><img id="BLOGGER_PHOTO_ID_5252044747207507106" style="DISPLAY: block; MARGIN: 0px auto 10px; CURSOR: hand; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5if9GkemYtngB3aLk8pZ0C-B3acrP0LpOYGnBFCs9ZWA0Rs9jS1q6QfJmh8_w7OptrF4mYrNdpQVr1JDxHY0pwyj4nUDr6xpmMC-72C0x7DeZFAbctArAacJsrXfwZMaIk5dS4veqiJZT/s400/DSCN0018.JPG" border="0" /><br />Figure 1. Large corn earworm larva on a wheat head. (Photo: R. Lloyd)<br /><br />All Helicoverpa larvae found feeding in wheat, barley or triticale crops will be corn earworm. The native budworm, <em>H. punctigera</em>, is not normally found on monocots (grasses). This is important to know, because the corn earworm has developed resistance to pyrethroids, and unless the larvae are small, a pyrethroid spray is unlikely to control them.<br /><br />If large larvae are present, identification becomes a somewhat academic issue. However, large <em>H. armigera</em> larvae can be identified by the white hairs behind the head (Figure 2). In contrast, the hairs on large <em>H. punctigera</em> larvae are black. These compare with armyworm larvae which have three pale stripes just behind the head, and smooth skin, without any hairs or bumps.<br /><div></div><br /><img id="BLOGGER_PHOTO_ID_5252045090254171778" style="DISPLAY: block; MARGIN: 0px auto 10px; CURSOR: hand; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1k-HqCjuz5Ea3QMYgqtcp1CiPtiCHe2aASkjOGT9fjdCF0HCDr25WQyGXiU_HOcU9vnBz7ePCgP-R7Ca5rqpFQjffVSBqX0q5IapnG2iDyJu_WGbq7ORkBMlQWR3xdl2LEiaLIzS0X32A/s400/heliothis+head2.jpg" border="0" /><br /><div>Figure 2. White hairs behind the head of corn earworm larva. (Photo: R. Lloyd)<br /><br />If corn earworm infestations are detected early and larvae are small, preferably less than 7 mm in length, <em>Helicoverpa</em> nucleopolyhedrovirus (NPV) sold as Vivus Max could be considered as it will not harm beneficials (predators and parasites) in the crop. Some caution is needed as NPV will not kill corn earworm larvae greater than 13 mm in length, and will have no effect on armyworms.<br /><br />Invariably when larvae are found on cereal crops, they are medium or large (>13 mm in length) and a more robust option is needed to control them. Both corn earworm and common armyworm are usually present in winter cereals, and control measures will be influenced by the relative abundance of each.<br /><br />Follow the link below for more information related to thresholds and control options.<br /><a href="http://thebeatsheet-ipmnews.blogspot.com/2007/10/are-corn-earworm-problem-in-winter.html">http://thebeatsheet-ipmnews.blogspot.com/2007/10/are-corn-earworm-problem-in-winter.html</a></div>BigBughttp://www.blogger.com/profile/11764696091701617022noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-44950788226874171292008-09-25T13:25:00.012+10:002008-09-25T14:00:23.573+10:00Cereal Aphids in wheat and barley Spring 2008Cereal aphid numbers have increased rapidly over the past 3 weeks as the temperatures have increased. Whilst low numbers of aphids have been present in many crops (wheat and barley) for some time, it was not until a couple of weeks ago that numbers reached levels of concern to agronomists and growers.<br /><br /><div><div><div>Until the last few seasons, cereal aphids have not been considered a major pest in winter cereals. However, higher grain prices mean that the value of any yield loss is higher than it was and control may be economic at the densities we are experiencing.</div><div></div><div><br /></div><div><strong><span style="font-size:130%;color:#ff0000;">Which species are in crops this season?</span></strong></div><div><br /></div><div>There are several species of aphid that occur in winter cereals (oats, wheat and barley). The most abundant, and the species that has been present in low numbers through winter are the <strong>oat aphid</strong> (<em>Rhopalosiphum padi</em> – it sounds like Row-pal-o-si-fum pad-i). This species tends to colonise the lower portion of the plant, mature adults are a dark green and rounded. Juveniles are paler and smaller.<br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvvqkC84CJ0IvinVIewbkeGH8nsMthf8bSIRGvzkPkUr-BB139BgQJW9mX2X-PWysou8s1UNJXV794D6Y0dOtM92Nbra4-6yJBQRLFFYFdN4QZThyMIOnh9x9wAv7gDfoWaJfMBB5ifwI/s1600-h/oataphid.gif"></a><br /><br /><strong><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjd0r3zYZTlykp3tHjeQhd-DlEmUBCHNl2E3V_Wah_MzdsKhI0gy1N0QnCzp_YUuowjmQkqIs0K0Kd4ic9Ir8AL4KyRpXkt6rzZrge13G35Gmkl-x5yZqWIjRoMcOaDEvJlAEK2gyHQjog/s1600-h/Cereal+Aphids+2008+019.jpg"><img id="BLOGGER_PHOTO_ID_5249799254955571490" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; CURSOR: hand" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjd0r3zYZTlykp3tHjeQhd-DlEmUBCHNl2E3V_Wah_MzdsKhI0gy1N0QnCzp_YUuowjmQkqIs0K0Kd4ic9Ir8AL4KyRpXkt6rzZrge13G35Gmkl-x5yZqWIjRoMcOaDEvJlAEK2gyHQjog/s320/Cereal+Aphids+2008+019.jpg" border="0" /></a></strong></div><div><br /></div><div><strong></strong></div><div><br /></div><div><strong></strong></div><div><strong></strong></div><div><strong></strong></div><div><strong></strong></div><div><strong></strong></div><div><strong></strong></div><div><br /></div><div><strong></strong></div><div><br /><br /></div><div><strong><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhMnqraCacnGfOr5C8RPxtBtOCZppsfQ2eL6TvH3haEdCwFsOzf7fz4l8mE1qqmSu78Gxlt8aWeoAPV1lQ12dQjgsqTF4qS-iMVj4SM8Qmypfsa0seh1IWKnq7dmDKMJ1QnTjNpXRHF9q4/s1600-h/oataphid.gif"><img id="BLOGGER_PHOTO_ID_5249799715175775922" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; CURSOR: hand" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhMnqraCacnGfOr5C8RPxtBtOCZppsfQ2eL6TvH3haEdCwFsOzf7fz4l8mE1qqmSu78Gxlt8aWeoAPV1lQ12dQjgsqTF4qS-iMVj4SM8Qmypfsa0seh1IWKnq7dmDKMJ1QnTjNpXRHF9q4/s320/oataphid.gif" border="0" /></a></strong></div><div><br /><br /></div><div><strong></strong></div><div><br /><br /></div><div><strong></strong></div><div><br /><br /></div><div><strong></strong></div><div><br /><br /></div><div><strong></strong></div><div><br /><br /></div><div><strong></strong></div><div><br /><br /></div><div><strong></strong></div><div><br /><br /></div><div><strong></strong></div><div><strong></strong></div><div><strong></strong></div><div><strong></strong></div><div><strong></strong></div><div><strong></strong></div><div><strong></strong></div><div><strong>On the Downs</strong>, the oat aphid is currently the dominant species, with infestations extending from around the base of plants up on to leaves and stems as the crop starts elongation. Smaller number of the rose-grain aphid and corn aphid are also present.</div><div><br /></div><div></div><div>The <strong>rose-grain aphid</strong> (<em>Metopolophium dirhodum</em> – sounds like meto-pal-o-fee-um di-road-um) is a large, pale aphid with a dark stripe down the midline of the back. This species tends to colonise leaves higher on the plant, and is often very obvious. Clusters of juveniles are common on upper surfaces of leaves.<br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_2jrKgFabHGfW9nsv3Qk2hi1GluCM-QLLh11Ya9DsfeRbItYzMTKk6vb5pKOuArZ7MDW6alKrRhd8yW-6xSBNAIfL-Gk3Wn886OSNrFxllu-GtkP92n_ooJOOoUA-4dL8c476k-mYs0U/s1600-h/Cereal+Aphids+2008+015.jpg"><img id="BLOGGER_PHOTO_ID_5249799249174725602" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; CURSOR: hand" height="183" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_2jrKgFabHGfW9nsv3Qk2hi1GluCM-QLLh11Ya9DsfeRbItYzMTKk6vb5pKOuArZ7MDW6alKrRhd8yW-6xSBNAIfL-Gk3Wn886OSNrFxllu-GtkP92n_ooJOOoUA-4dL8c476k-mYs0U/s320/Cereal+Aphids+2008+015.jpg" width="250" border="0" /></a><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg7OSEbpiQGXY2RsRmV-8JsKSJZJuGYjmQCgdl0Zt9SfBNncQN4WICeyIDPO6AXVahh0k_k7wEFMlRAR_UZ46OrwgHPfWDqZMmsiVKCUW_au88-hrG-Oba_EMHx6npHUsaD0Ez0DXzZUZI/s1600-h/rosegrainaphid_insectopedia.gif"><img id="BLOGGER_PHOTO_ID_5249800587478440738" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; CURSOR: hand" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg7OSEbpiQGXY2RsRmV-8JsKSJZJuGYjmQCgdl0Zt9SfBNncQN4WICeyIDPO6AXVahh0k_k7wEFMlRAR_UZ46OrwgHPfWDqZMmsiVKCUW_au88-hrG-Oba_EMHx6npHUsaD0Ez0DXzZUZI/s320/rosegrainaphid_insectopedia.gif" border="0" /></a><br /></div><div><br /><br /></div><div></div><div><br /><br /></div><div></div><div><br /><br /></div><div></div><div><br /><br /></div><div></div><div><br /></div><div></div><div></div><div></div><div></div><div></div><div>The <strong>corn aphid</strong> (<em>Rhopalosiphum maidis</em> – sounds like Row-pal-o-si-fum may-dis) is rectangular in shape rather than round. Legs and antennae are typically dark, the body green-blue, and they may look waxy.<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOMnluPfjv_fHAndygkXuEeLZwT1RS4HS4Qd1I1zNfxuxFRz5suEKHpZWlzAhFA9_hIRUcUo-6i56jO_37CH7mtoHauutz602UDltaau-n7-DFB5mfDycYuVIHJt1Zb6wwdJ8iNs2s8RE/s1600-h/cornaphid.gif"></a> </div><div><br /><br /></div><div></div><div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4S9XmiG-K6nCmEFh7TvizHq4g-r-wP8_4KCgP9xMPc1da3wJRRE-YGNCvKbqPH9Ic_kjLF336aDZWAYOaWaOSnyLYlRuDhgVHdkvNJpZ1K0LcKZZK3WRhpouC3pYbBn7plTq5GIn_cI0/s1600-h/Rmaidis_id.jpg"><img id="BLOGGER_PHOTO_ID_5249799261117480770" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; CURSOR: hand" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4S9XmiG-K6nCmEFh7TvizHq4g-r-wP8_4KCgP9xMPc1da3wJRRE-YGNCvKbqPH9Ic_kjLF336aDZWAYOaWaOSnyLYlRuDhgVHdkvNJpZ1K0LcKZZK3WRhpouC3pYbBn7plTq5GIn_cI0/s320/Rmaidis_id.jpg" border="0" /></a><br /></div><div></div><div><br /><br /><br /></div><div></div><div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjNdiRainGRrMWCYy4JxZBSAbmUy4fDg-kjK1viiqpwmaw426G4-DB7VhlD5zKTvSbm7oiOR_k8CJZ2e7Qios6wf2Ta4YW7zoicArd07QywmpNzodJhFfoK2iK0gQvtJtNej76NMQJuQ8/s1600-h/cornaphid.gif"><img id="BLOGGER_PHOTO_ID_5249799712619842930" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; CURSOR: hand" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjNdiRainGRrMWCYy4JxZBSAbmUy4fDg-kjK1viiqpwmaw426G4-DB7VhlD5zKTvSbm7oiOR_k8CJZ2e7Qios6wf2Ta4YW7zoicArd07QywmpNzodJhFfoK2iK0gQvtJtNej76NMQJuQ8/s320/cornaphid.gif" border="0" /></a><br /><br /></div><div></div><div><br /><br /></div><div></div><div><br /><br /></div><div></div><div><br /><br /></div><div></div><div><br /><br /></div><div></div><div><br /><br /></div><div></div><div> </div><div></div><div><span style="font-size:78%;"></span></div><div><span style="font-size:78%;">(line drawings from “Insectopedia” Agriculture Victoria, 2000)</span></div><div><span style="font-size:85%;"></span></div><div><br /></div><p align="center"><strong><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivx0mCgwk_prHqzm5NDbXjd3-PDttij9sX6bQxWCFh1OLbg-EDxVNeijVO9gZ9tIApblFo0pyBnPlNj9NKUSelKNUVhjW_iQ5Qk5bT2nYe3pakuyIkn4GBzMhAF7-QoOTDPe63nkacegI/s1600-h/Cereal+Aphids+2008+055.jpg"><img id="BLOGGER_PHOTO_ID_5249801284603140770" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; CURSOR: hand" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivx0mCgwk_prHqzm5NDbXjd3-PDttij9sX6bQxWCFh1OLbg-EDxVNeijVO9gZ9tIApblFo0pyBnPlNj9NKUSelKNUVhjW_iQ5Qk5bT2nYe3pakuyIkn4GBzMhAF7-QoOTDPe63nkacegI/s320/Cereal+Aphids+2008+055.jpg" border="0" /></a></p><div>In northern NSW</strong>, the corn aphid is abundant higher in the canopy, particularly in crops that are booting. Corn aphid is reputed to decline in number as the crop comes out into head.<br /></div><div>The photo illustrates a typical corn aphid infestation in a crop of barley prior to head emergence.<br /></div><div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivx0mCgwk_prHqzm5NDbXjd3-PDttij9sX6bQxWCFh1OLbg-EDxVNeijVO9gZ9tIApblFo0pyBnPlNj9NKUSelKNUVhjW_iQ5Qk5bT2nYe3pakuyIkn4GBzMhAF7-QoOTDPe63nkacegI/s1600-h/Cereal+Aphids+2008+055.jpg"></a></div><div></div><div></div><div></div><div><br /><br /><br /><br /></div><div><br /><strong><span style="font-size:130%;color:#ff0000;"></span></strong></div><div><strong><span style="font-size:130%;color:#ff0000;"></span></strong></div><div><strong><span style="font-size:130%;color:#ff0000;"></span></strong> </div><div><strong><span style="font-size:130%;color:#ff0000;"></span></strong> </div><div><strong><span style="font-size:130%;color:#ff0000;"></span></strong> </div><div><strong><span style="font-size:130%;color:#ff0000;"></span></strong> </div><div><strong><span style="font-size:130%;color:#ff0000;"></span></strong> </div><div><strong><span style="font-size:130%;color:#ff0000;"></span></strong> </div><div><strong><span style="font-size:130%;color:#ff0000;"></span></strong> </div><div><strong><span style="font-size:130%;color:#ff0000;"></span></strong> </div><div><strong><span style="font-size:130%;color:#ff0000;">How much damage can aphids cause?</span></strong></div><div><br /></div><div>There has been surprisingly little work done on cereal aphids in Australia to establish the relationship between aphid numbers, the duration/timing of infestation, aphid species, and ultimately the impact on yield. </div><div><br /></div><div>Direct aphid damage, as a result of feeding, is difficult to detect. In moisture stressed crops you may see yellowing with high aphid populations. Otherwise, there are generally no early signs of how much impact the aphids are having on the crop.Western Australian recommendation are to <strong>check crops regularly from late tillering, and consider control if the aphid population exceeds 15 aphids/tiller on 50% of tillers</strong>. </div><div><br />The WA research showed yield losses of up to 10%, and reduction in seed size, with aphid infestations (this was without any impact of barley yellow dwarf virus).</div><div><a href="http://www.agric.wa.gov.au/content/pw/ph/dis/cer/bydv_aphidfeeding.htm">http://www.agric.wa.gov.au/content/pw/ph/dis/cer/bydv_aphidfeeding.htm</a><br /></div><div><br /><br /></div><div>Queensland DPI&F recommendations have been to:<br /><strong>Check 5 plants at 6 sites within the field. If 27/30 (90%) of plants are covered with aphids, and there are less than 2 natural enemies per plant, then consider treatment.</strong> </div><div><br /></div><div>A 90% infestation level would be indicative of a well established population. Early infestations tend to be patchy, and become more uniform as the population builds up.</div><div><br /></div><div></div><div><strong><span style="font-size:130%;color:#ff0000;">Checking a crop for aphids</span></strong><br />Sample away from the edge of a field. Aphid numbers tend to be higher around field margins because this is where initial infestations start. The rest of the field will be more representative of the infestation in the majority of the field.</div><div><br /></div><div>It is simpler to base estimates of infestation on tillers rather than whole plants. It can be difficult to determine where an individual plant starts and stops, and the number of tillers per plant can be variable. </div><div><br /></div><div>Taking a representative sample of individual tillers from across a field will provide information on the number of aphids, and the proportion of the tillers infested. The lower the infestation the more tillers you will need to sample (e.g. 30 per management unit). The more established the population the more uniform the infestation will be and the number of tillers sampled can be reduced (e.g. 10-20 tillers may be sufficient). Record the number of aphids per tiller and see how consistent numbers are as you go. Lots of zeros means the population is patchy.</div><div><br /></div><div>If numbers are high, you may want to use a rating system for estimating density rather than actually counting aphid numbers.<br />For example: 0= no aphids, 1= 1-10 aphids, 2= 10-20 aphids, 3= 20-50 aphids, 4= more than 50 etc. Once you have your eye in, a rating system is quicker than counting aphids. </div><div><br /></div><div>It may be useful to rate the number of aphids above and below the flag leaf separately. This will be particularly useful for assessing how effective a spray has been, and determining if surviving aphids are those that may have simply not been contacted.</div><div><br /></div><p><strong><span style="font-size:130%;color:#ff0000;">Information from overseas research (Canada, US) suggests:</span></strong><br /></p><ul><li>that significant yield loss occurs when aphids are present from the flag leaf stage through to milky grain – no yield loss occurs with infestations later than milky grain<br /></li><li>infestations of aphids on the flag leaf, and upper portions of the crop, including on the heads, cause greater yield loss than infestations lower in the canopy</li></ul><div><strong><span style="font-size:130%;color:#ff0000;">Other considerations when making a decision about cereal aphids<br /></span></strong></div><ul><li>Corn aphids may disappear by themselves. Corn aphids, the species that colonises the upper canopy, reputedly decline in number when the crop comes into head. This may be because they tend not to survive as well on leaves as they do on the flag leaf or in the whorl.<br /></li><li>Natural enemies (lady beetles, hoverflies, parasitic wasps) can have a big impact on aphid populations, reducing them to very low levels in many instances. This is particularly important in managing the resurgence of any aphids that survive a spray.<br /></li><li>Dimethoate and synthetic pyrethroids (e.g. Bulldock®) are highly disruptive to natural enemies. The application of these insecticides early may result in a later reinfestation of the crop because small numbers of surviving aphids are no longer controlled by natural enemies. The impact of these products on natural enemies can persist for some days.<br /></li><li>Pirimicarb (e.g. Pirimor®) is a soft option for cereal aphid control, but be aware of the with-holding period.<br /></li><li>there is no Australian data on resistance to any of the registered insecticides in cereal aphid populations.<br /></li><li>Oat aphids, at the base of the plant, can be difficult to contact in a dense crop, and with aerial application.<br /></li><li>Rain will reduce aphid populations by knocking/washing individuals of plants, particularly if the rain is high intensity (storm) rain. When washed off, aphids tend not to get back on the plants. Often ground predators, like carabid beetles, ants etc will eat aphids on the ground. It may be worth re-checking numbers if you get a storm between checking and applying a spray.</li></ul></div></div>bugladyhttp://www.blogger.com/profile/13351824435251392456noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-58020310009384820232008-04-17T15:10:00.013+10:002008-04-21T12:43:06.923+10:00Farm hygiene important in pest management<div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhNXefqNLc6LRO08pzIAxVTEA3PdfG-kU8cIvLNkPUJYUZ-aaXS8PCHzxRVsWzi_nBhAdCA9y44DzbLF0ql6JG2sMQaP4SFw9FA7Eg4RY3zhBbAgCMNSjFXSKzQGMuUhWqpofrvqREHGks/s1600-h/RIMG0011.JPG"><img id="BLOGGER_PHOTO_ID_5191521839750704514" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; CURSOR: hand" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhNXefqNLc6LRO08pzIAxVTEA3PdfG-kU8cIvLNkPUJYUZ-aaXS8PCHzxRVsWzi_nBhAdCA9y44DzbLF0ql6JG2sMQaP4SFw9FA7Eg4RY3zhBbAgCMNSjFXSKzQGMuUhWqpofrvqREHGks/s320/RIMG0011.JPG" border="0" /></a> <span style="font-size:130%;color:#3333ff;"><strong>David Murray, Toowoomba</strong></span><br /><div><br /><div><div><div><div><div></div><div>Farm hygiene is an important component of integrated pest management (IPM), particularly when it comes to managing pests such as cotton aphids and Cotton Bunchy Top (CBT) disease.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjav6TmUlBuFlFFWej9kXIpFxZiqJf3JaVpxO18BMonJ6SkHwkI_ZqAEIGvY88EY51iUPYtj5PFKaa1LGGKh024vlNs00ALZi3qd4tEPENGYGYjx8dxp0DymP6wy33Apse0OEmxOjaO2Kk/s1600-h/CBT_cotton1_LWilson.jpg"><img id="BLOGGER_PHOTO_ID_5191515951350541650" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 208px; CURSOR: hand; HEIGHT: 254px" height="245" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjav6TmUlBuFlFFWej9kXIpFxZiqJf3JaVpxO18BMonJ6SkHwkI_ZqAEIGvY88EY51iUPYtj5PFKaa1LGGKh024vlNs00ALZi3qd4tEPENGYGYjx8dxp0DymP6wy33Apse0OEmxOjaO2Kk/s320/CBT_cotton1_LWilson.jpg" width="150" border="0" /></a>Recent surveys of cotton-growing areas indicate the presence of aphids and CBT, and wetter conditions through the coming winter could favour the growth of weeds that are hosts for aphids and also increase survival of cotton volunteers that carry CBT to the next season. </div><br /><div></div><div><strong><span style="font-size:85%;">The photo (right) shows volunteer cotton with CBT symptoms adjacent to the current season cotton crop (Photo: Lewis Wilson, CSIRO)<br /></span></strong><br />CSIRO and Cotton CRC entomologist Dr Lewis Wilson suggests that growers maintain good farm hygiene to reduce the risk of aphid or CBT problems next season.<br /><br /><br />CBT can stunt the growth of cotton plants and, if plants are infected when young, dramatically reduce yield.<br /><br />CBT is spread by cotton aphids when they feed. Both cotton aphids and the disease need a host plant for survival through winter. <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjnxsoUwivfyNXDASkgcDxj25r3YT5BaRYX-X_QP3aJMQtoLe-yX_kBl3_bKu2mIPt5nOrwiTjl-8ywy5ZPWgrnuc6EYsHd0uTrBDOAWbhe9Z5BvkGvXz_wqjQ0T01Au-nxZatTGfdDFbo/s1600-h/CBT_fallow_volunteers_LWilson.jpg"><img id="BLOGGER_PHOTO_ID_5191515556213550370" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; CURSOR: hand" height="188" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjnxsoUwivfyNXDASkgcDxj25r3YT5BaRYX-X_QP3aJMQtoLe-yX_kBl3_bKu2mIPt5nOrwiTjl-8ywy5ZPWgrnuc6EYsHd0uTrBDOAWbhe9Z5BvkGvXz_wqjQ0T01Au-nxZatTGfdDFbo/s320/CBT_fallow_volunteers_LWilson.jpg" width="235" border="0" /></a><br /><br />Cotton is a good host and volunteer or ratoon cotton plants can be found on farms all year. These plants can carry the disease and aphids through winter. Aphids can then move to cotton crops in the following spring and infect plants with the disease. </div><div> </div><div><strong><span style="font-size:85%;">Photo: Fallow field with a high number of volunteer cotton plants, a potential resevoir for cotton aphid and CBT (Lewis Wilson, CSIRO).<br /></span></strong><br />While it is likely that CBT will survive on alternative weed hosts, these relationships have not been studied.<br /><br />In recent field inspections on the Darling Downs, cotton volunteers were found on virtually every farm. </div><div> </div><div><strong><span style="font-size:85%;">Many of these volunteers showed clear symptoms of CBT, such as angular leaf mottling and small leaves (see photo below, Photo: Lewis Wilson, CSIRO). </span></strong></div><div><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvrpjapdZ6DE-llTlrwytf4e3adyUGFRClMO3d1XhyH96_BXnRpBzhMIqpXmAdb-lDZAaASBThpCToCjtx12AqFQ8J_T-sjD8TkWUhLFjj_1otwd6GcWturXhc3uK-j267Rq-xBcBUEPU/s1600-h/CBT_symptom_LWilson.jpg"><img id="BLOGGER_PHOTO_ID_5191522239182663058" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; CURSOR: hand" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvrpjapdZ6DE-llTlrwytf4e3adyUGFRClMO3d1XhyH96_BXnRpBzhMIqpXmAdb-lDZAaASBThpCToCjtx12AqFQ8J_T-sjD8TkWUhLFjj_1otwd6GcWturXhc3uK-j267Rq-xBcBUEPU/s320/CBT_symptom_LWilson.jpg" border="0" /></a></div><p align="left"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsBdijGTYtZ3WMKsf3IiHgvwjhmk7YZ_dIHBgZykV1jAraUZVQj5Xtv_aZs7esce10EkBchHmisRbOe9sd_Qr7Muos5n_nHBRQqmLx41wo67ZJ2gBORJuCcmo4YFL5rRyg7bWxCWFzEo4/s1600-h/CBT_symptom_LWilson.jpg"></a></p><div>Cotton CRC extension officer Rod Gordon said that regular rainfall through the summer had encouraged growth of cotton volunteers, many of which were glyphosate-tolerant and difficult to control with herbicides. Wet fields have also limited opportunities to control volunteer cotton, with some fallow fields and field margins containing quite high densities.<br /><br />The importance of controlling volunteer cotton in fallows can not be stressed enough. Minimising host availability is critical to ensure that we do not see a repeat of the 1998 CBT outbreak.<br /><br />More information on cotton aphid and CBT can be found on the Cotton Catchment Communities CRC website at<br /><a href="http://www.cottoncrc.org.au/content/Industry/Publications/PestsandBeneficials/CottonBunchyTopCBTCharacteristicsandModes.aspx">http://www.cottoncrc.org.au/content/Industry/Publications/PestsandBeneficials/CottonBunchyTopCBTCharacteristicsandModes.aspx</a> </div></div></div></div></div></div></div>bugladyhttp://www.blogger.com/profile/13351824435251392456noreply@blogger.com0tag:blogger.com,1999:blog-7115720169493343649.post-5364219413851303862008-03-27T11:48:00.003+10:002008-03-27T11:55:08.629+10:00Accessing the Diapause Tool - An alternative addressIf you are having trouble with the link to the Diapause tool provided in the story below, try the following:<br /><br /><a href="http://tools.cottoncrc.org.au/xl2/diapause/index.aspx">http://tools.cottoncrc.org.au/xl2/diapause/index.aspx</a>bugladyhttp://www.blogger.com/profile/13351824435251392456noreply@blogger.com0