Annually, we conduct a survey to estimate corn earworm infestation levels in field corn in late July. Earworms develop in corn, then move to other crops such as soybean, cotton, and peanut in August. We determined the number of corn earworms found in 50 ears of corn from 5 randomly selected corn fields in each of 24 counties, totaling 5,800 ears and 116 fields sampled. Statewide, 42% of ears were infested with earworms. This is up from 36% in 2009. Regional averages were 12% infested in Northern, 28% in the Northern Neck, 39% in Mid-Eastern, 58% in the Southeast, and 46% on the Eastern Shore. See the attachment with results from each county and many more details. From the survey, it looks like the areas of greatest risk to heavy infestations of earworms are the southeastern ‘cotton/peanut’ counties, and the Eastern Shore. However, as large as this effort is, it is not a complete picture. We always recommend scouting individual fields to determine exactly what is happening in terms of corn earworm as well as other pests and crop problems. We will continue posting moth catch numbers and other information regarding the 2010 insect pest situation.
Additional information: cew-survey-table10-2-docx

I am paraphrasing an email we received from Jack Bacheler at NC State last week alerting us to a new invasive insect pest of soybeans. The Figure images (Fig. 1, Fig. 2, and Fig. 3) are attached:

The bean plataspid, Megacopta cribraria Fabricius, is a new invasive pest from south Asia that is currently spreading throughout the southeastern United States (Fig. 1). This insect is a piercing sucking pest (similar feeding as stink bugs) on legumes and was first found on kudzu in Georgia during December 2009. It has since been confirmed on both soybeans and kudzu in both Georgia and SoI am paraphrasing an email we received from Jack Bacheler last week alerting us to a new invasive insect pest of soybeans. The Figure images (Fig. 1, Fig. 2, and Fig. 3) are attached: uth Carolina in 2010. The confirmed distribution is represented in Fig. 2.

Research on insecticide management options is being conducted by Dr. Phillip Roberts, University of Georgia, and his colleagues. The University of Georgia researchers and Dr. Jeremy Greene, Clemson University, are monitoring this pest and we need to be vigilant for the appearance of this pest in North Carolina. Many invasive insects are found in extremely high numbers upon initial establishment, which may aid in our detection of this pest (Fig. 3). Current numbers from Georgia in soybeans are reported as close to 10 insects per sweep near field borders, where the distribution of this pest is the highest.

Please contact me if you see this insect in your soybean field (Ames Herbert, 757-657-6450, ext 411, Herbert@vt.edu).
Additional information: bean-plataspid-jul-22-2010-ppt

Corn earworm is on the rise. Trap catches started increasing this week, up from near zero last week, and we are seeing moths flying in soybean, peanut and cotton fields. The worst news on corn earworm relates to the resistance monitoring program. As in the past several years, we are testing live-caught male moths in what we call the AVT program (adult vial test). Live moths are placed individually into small glass vials pretreated with a known amount of cypermethrin (the pyrethroid used throughout the south in the AVT program). We check the vials in 24 hours and any live moths are considered to be ‘survivors’ demonstrating resistance. Although we have only tested 363 moths to date, we found that 48% survived in this week’s sample (see the attached chart). This is the highest level ever recorded in Virginia. Last year we found about 40% survivorship in some later season samples, which was the highest level for the years up to 2009. We will continue posting the AVT results, but all indications are that we may be in for some pyrethroid control issues again this summer. Additional information: cew-avt-jul-22-2010-ppt

Attached is a Belay Supplemental label that has been approved by the EPA and is pending state approval. This Supplemental Label allows Belay to be applied aerially in soybeans, cotton, and potatoes. In addition, the aerial use rate is 3 to 6 fl oz/A. This is a higher use rate than the current ground application label (3 to 4 fl oz/A); however, the EPA has approved the change of the use rate for Belay when applied by ground in soybeans and cotton. That Supplemental Label will be out this coming week. Additional information: belaysuppl-label-aerialappl-2010-bel-0015-xcaflny-pdf

Grasshoppers are always worse in dry years. They tend to move from border vegetation or infield weed sources as they dry down (which occurs more readily in dry weather), or from cover crop after herbicide burn down. They will undergo several generations—we find hoppers in all sizes (nymphs and adults) almost any time during the season, especially as we move into late summer/fall. They will eat soybean leaves, but are also capable of feeding on young pods later in the year. Treatment this time of year has to be based on the extent of defoliation. Under normal growing conditions, soybeans are capable of withstanding a lot of defoliation (30-40%) in the vegetative growth stages because they are growing so rapidly constantly putting on new canopy. Of course under these dry conditions, they are standing still, almost. You have to gauge the need for treatment on this tough decision point and it is often a seat-of-the-pants call, as many of them are. If the defoliation is severe and hoppers are abundant, I think you need to consider a treatment. Treating field edges can be effective, especially if hoppers are still moving in from bordering weed sources. If we do not get rain enough to make a decent crop, control efforts and the $ spent will have been wasted—a hard call to make If treatments are made, our limited experience showed that products containing chlorpyrifos (Lorsban 4E at ½ to 1 pt/acre, or Cobalt at 7 to 13 oz/acre) were more effective than pyrethroids. All things considered, I would use the lowest labeled rate. Also, Lorsban 4E is pretty good for controlling twospotted spider mite, which may also be present, or at least a pending threat.

The dry weather has provided the perfect opportunity for spider mite flares. We have reports of infested soybean fields in Charles City County and some in the Suffolk/Southampton County area. Miticide options are limited in soybean to bifenthrin (Capture, Brigade, and others), dimethoate, and Lorsban 4E. Bifenthrin is a pyrethroid so products will provide knock down of adults and nymphs, but not control of eggs. If there are a lot of eggs present at the time of application, they will hatch and could require a second application within 5 days or so of the first. Dimethoate is a foliar systemic but must be absorbed and translocated by the leaf tissues to provide residual action; otherwise, it undergoes rapid photodecomposition from sunlight. This leaf absorption process is greatly reduced in drought-stressed plants that have “shut-down” physiologically. According to Dr. Whalen (Univ. of Del), another important factor that plays a role in the performance of dimethoate is the pH of the water used as the carrier. Many pesticides, especially dimethoate, are subject to breakdown by alkaline hydrolysis. In alkaline water (high pH), dimethoate break down can result in poorer than expected field performance. Dimethoate degradation is also accelerated by the mineral content of the water, especially the presence of iron. If a high pH situation exists, you can lower the alkalinity of the water in the spray tank by adding an acid-based buffer. The buffer must be added to the spray tank first, before the addition of dimethoate. Lorsban 4E is somewhat effective against mites and offers the advantage of also having good activity against grasshoppers and some other pests. The very best control for spider mites is rain. I wish I could ‘recommend’ that but I reckon my ‘connections’ are not quite that good, yet!

A lot of soybean fields in Northampton County, particularly in the Cape Charles area, suffered some late-season defoliation from soybean looper. There was a lot of concern about insecticide resistance in this often difficult-to-control pest, particularly after loopers appeared in fields after being sprayed with a pyrethroid. After hearing reports from some growers and cooperators and their experiences, pyrethroids such as Baythroid and Warrior, were effective against this pest if you got good coverage and penetration into the canopy. Also, follow-up sprays of Warrior appeared to clean up the larvae in some of the problem fields. It is more than likely that some of the soybean looper infestations that we had on the soybeans in Northampton County following sprays of Warrior or another pyrethroid were a result of poor coverage or possibly bad timing. It would have been very difficult for a low volume aerial application to penetrate all of the foliage that we had on our dense soybean canopies this year in Northampton County. It is possible that soybean loopers fed on untreated leaves in the lower canopy, then moved on to the pesticide covered upper foliage after the residual was gone.

Looks like soybean aphids are not done yet in Virginia. And, I received a call today about a possible threshold situation in northeast North Carolina. Growers have treated some fields in the areas where thresholds were met last week. We have learned of a new area in King George County where aphids have exceeded thresholds, in a very late planted field, in about the R3-R4 growth stage. We are having a cooling trend which will favor these critters, and will slow bean maturity. Unless we can come up with some ’emergency’ funds, we have to discontinue our scouting program at the end of next week. We really need to go for at least 2 or 3 weeks. By then, the double crop will have reached the safe stage (R6).

Soybean Aphids: We are seeing an increase in soybean aphid numbers in the same areas we reported last week. I heard today that populations were building in one new area, on our Eastern Shore. Aphid populations are often mixed with corn earworms and stink bugs and although none are at threshold, the combination is making growers nervous. Several have applied insecticides. We are continuing our aphid survey of about 30-40 fields until mid September (when the funds run out). We will have an update on the situation when our scout reports in this Friday.
Corn Earworms: Corn earworms are still showing up in a lot of fields, but threshold levels are spotty. Moths are flying and some areas are still reporting fairly high numbers. Many soybean fields, mostly the double crop fields, are still susceptible to worm damage and will be for at least three more weeks. We are encouraging growers to continue scouting. Attached is a one page handout with ‘bullet points’ regarding the current corn earworm situation.
Stink Bugs: We are finding very large stink bug populations in a few fields, and a few in most. Of the fields we are surveying, the greatest majority are green stink bugs. Stink bugs seem to ‘pile’ up in soybean fields as the summer progresses, and into the early fall weeks. We are doing some field cage studies to try to sort out what these bugs are doing to bean yields and seed quality. For now, we should abide by the thresholds. On a positive note, our field trials over the last few years have shown that standard pyrethroids provided excellent control of green stink bugs.

Additional information: herbert-cew-25-aug-2009-doc

We are now hearing of threshold levels of corn earworm scattered across the region. Infestations are spotty. For example, we are not finding many worms in Chesapeake, VA Beach or Suffolk but have heard of infestations in several other areas. As many beans are still a long way from safe (R7), we may see more fields reach threshold as we get closer to Labor Day.