Although we are beginning to catch a few more moths than last week, we are still between generations. If things go according to previous patterns, the second generation will peak at a time to coincide with when field corn is developing ears. Some fields are beginning to tassel, so it won’t be long. We will be tracking and posting our trap catch and AVT (adult vial pyrethroid test) results weekly.
Category Archives: Insect
Tomato spotted wilt virus (TSWV) in peanuts and home garden tomatoes
Incidence of TSWV is increasing in the peanut crop. We have the advantage of having a lot of peanut thrips trials evaluating varieties and many insecticide control options where we are also able to rate TSWV severity. Hopefully, we will find the most effective alternatives for minimizing both thrips and the disease. We are also getting reports from home gardeners that tomato plants are showing disease symptoms. When disease symptoms begin to express in a plant, there is essentially nothing that can be done to decrease the severity. Some feel that removing infected tomato plants will prevent, or at least minimize the risk of transmission to other plants. Maybe, but the transmission has to occur from adult thrips that acquired the virus by feeding on infected plants while in the larval stage. An insecticide protection regime designed to control thrips can help a lot in reducing the spread of the virus from plant to plant.
Spider mites in soybean
We diagnosed a very heavy spider mite infestation on a soybean seedling sample from the Northern Neck area but are not hearing of widespread problems…yet. Although some areas got some decent amounts of rainfall over the last weekend, some areas are still pretty dry with conditions very conducive to spider mite outbreaks. If treatments are needed, Dimethoate is likely the best product choice as it has efficacy against adults and immatures, and some systemic activity. But, according to one of the suppliers with Cheminova, it is important to be certain the product is newly manufactured and has been stored properly. If the product is old or has been exposed to extreme high and low temperature fluctuations, it can be ‘denatured’ which greatly reduces its efficacy.
New 2ee label for use of acephate on field borders for stink bugs
United Phosphorus, Inc (UPI) has issued a FIFRA Section 2(ee)
recommendation with Acephate 97UP for the suppression of brown marmorated
stinkbugs for field borders, fence rows, ditch banks and borrow pits. The
states include Delaware, Pennsylvania, Virginia, New Jersey, West Virginia
and Maryland. Attached is the 2(ee) recommendation below. Should you have
questions please feel free to contact:
Tony Estes
United Phosphorus, Inc.
Cell Phone: 864-202-7526
tony.estes@uniphos.com
Click more for attached file of 2ee label.
Additional information: 2011-06-07-2-ee-acephate-97up—bmsb-field-borders-pdf
Stink bugs in field corn
Recent reports of stink bugs feeding in the whorl of field corn have come to my attention. There was no word on what species of stink bug they were, or how extensive the damage is, but whichever stink bug it is, their piercing-sucking mouthparts can reach the growing tip of young corn plants. Insecticides labeled to control stink bugs in field corn are available and can be accessed from Virginia Tech’s Cooperative Extension Pest Management Guide for field crops. Disclosure, I don’t have any efficacy data on stink bug control in field corn. This is largely due to the sporadic nature of these pests over the years.This picture has changed with the recent invasion of the brown marmorated stink bug in Virginia. That said, I tend to lean toward FMC products Hero 15EC and Stallion 15EC, which combine two insecticides. Hero contains two pyrethroids: bifenthrin and zeta-cypermethrin and Stallion contains one pyrethriod and one organophosate: zeta-cypermethrin and chlorpyrifos. One note of caution, if you’re going to use either of these products, I recommend using the high rates, because brown marmorated stink bugs have the tendency to re-invade. Also, the next potential threat to field corn from brown marmorated, or other stink bugs, is when corn begins to enter the reproductive stage. Contact: Rod Youngman, youngman@vt.edu, 540-231-9118 (office), 540-357-2558 (cell).
Early season corn earworm activity and control options in sweet corn
Over the past couple of weeks many areas of Virginia experienced some unusually high corn earworm moth activity. This early brief peak of moths was not typical, was likely not the result of migratory moths coming up from the southern U.S., but rather was the result of overwintering corn earworm pupae in Virginia and the fact that we had record high densities of this pest last summer. Nonetheless, this early blip in activity has pretty much run its course. However, if sweet corn was at a vulnerable state (tassel or later), there could be much more “worm” pressure on early sweet corn.
Based on 30 years of monitoring, the major flight of corn earworms will likely occur in mid-July in Virginia.
I’ve attachded a summary of our sweetcorn insecticide research data at Virginia Tech. Click “More” to get this report.
Best regards,
Tom Kuhar Additional information: kuharsweetcorn-ipm-handout-2010-doc
Please report any observations of the brown marmorated stink bug
Greetings growers, crop consultants, researchers, and extension personnel in Virginia. Several entomologists in the mid-Atlantic U.S. are now desperately trying to elucidate the biology and ecology of the new invasive brown marmorated stink bug, which has plagued many homeowners and tree fruit producers among others in Virginia. The pest potential of this stink bug to Virginia Agriculture is tremendous. We need your help with spotting various life stages of the bug around your garden, yard, or farm. We want to document what plants the bugs are getting on and when, and are they reproducing. So, I’ve attached a Word file (click More) of the life stages of this bug to help you identify it. I’m asking you to please e-mail me any spottings of the bug on plants that you make. Record the bug’s life stage, your location, host plant, and if any injury was observed. These anecdotal reports will be very valuable to us.
Many thanks,
Tom
Thomas P. Kuhar
Associate Professor
Department of Entomology
Virginia Tech
216 Price Hall
Blacksburg, VA 24061-0319
Office: 540-231-6129
Cell: 757-710-9781
Fax: 540-231-9131
e-mail: tkuhar@vt.edu
Additional information: brown-marmorated-stink-bug-lifestages-docx
Thrips update, a tough year
We are definitely having a tough thrips year in cotton, somewhat less in peanut. Growers have reported less control than normal with treatments of Orthene/Acephate, even at rates that used to provide good control. Two things may be happening. One is that treatments did kill a lot of thrips but fields are being continually invaded by adults, especially from nearby grain fields that are drying down. Or, earlier treatments killed most of the tobacco thrips and left or ‘encouraged’ outbreaks of western flower thrips that are much less susceptible to Orthene/Acephate. The only way to confirm a western thrips population is to provide our lab with a soapy/jar sample of clipped seedlings. We rinse them from the plants and ID them using a microscope. Without the knowledge of what species are present, it becomes a question of what insecticide to use. We are rating trips trials daily to generate the data to help guide that decision. For example, in one test we made two foliar applications, the first at bud stage and the second in 7 days. As of this week, we had an average of 71 thrips larvae in the 5-plant sample from the untreated control (definitely a lot of pressure). Orthene 97 at 4 oz provided 87% control, Radiant at 6 oz provided 78% control, Vydate C-LV at 17 oz 77% control, Lannate 2.4LV at 12 oz 67% control, and Karate Z at 1.28 oz 8% control. There were two surprises. Dimethoate 4EC at 8 oz provided 95% control, but this is higher than we have ever seen previously with this product and it may be a ‘misread’. And, the new product Benevia 10OD (Cyazypyr) by Dupont, which is not labeled yet, provided 98% control.
Here are a few thoughts based on these data and what we are seeing in fields. First, cotton in many fields is close to being in the 4-5 true leaf stage, on the other side of the thrips pressure period when no further thrips treatments are needed. With the recent rains and warm-hot weather, we will see a lot of growth in the next week. Second, there does not seem to be a ‘silver bullet’ product for thrips control as some may lead you to believe. Orthene/Acephate is still hard to beat, with the exception of this new Benevia which is not labeled, yet. But there is a risk to multiple applications of Orthene. It is tough on beneficial insects and could lead to a much higher risk to flaring mites and aphids….remember that Temik was providing early season suppression of both of these pests. If a second spray is being considered (still seeing damage to the new bud), it might make good sense cost-wise to shift to Dimethoate at 8 oz, which seems to work pretty well and can provide some control of spider mites (is used by soybean growers for spider mite control in DE and MD). The cotton entomologist at Univ of Georgia also recommends Bidrin at 3.2 oz. I have not tested Bidrin, but trust his knowledge.
We will continue to monitor thrips and our many research trials and look forward to sharing our result at our upcoming field tour on June 2.
Corn earworm pyrethroid vial test results–alarming early season results
We have initiated our annual program to assess adult corn earworms (moths) for susceptibility to pyrethroid insecticides. As you may recall, this process has been in place for many years throughout much of the southeast. Adult corn earworms (moths) are captured live and placed individually into small glass vials pretreated with either a pyrethroid insecticide, or untreated as a ‘control’. After 24 hours, vials are inspected to determine the number of dead (susceptible) and alive (resistant) moths. Each year we capture and test as many corn earworm moths as we can manage to track the percent that survive. This survival percentage is at least an indicator of how susceptible corn earworms are to applications of the many pyrethroid insecticide options for growers.
We are already seeing some alarming results. First, our moth captures are very high for this early in the season. As of this week (May 23-27), we have already captured and tested over 200 moths, many more than last year at this time. The largest sample was tested mid week and 25% survived. This is a very high early season survival rate compared with previous years and is not a good way to start the season. We will press to capture and test as many corn earworm moths as we can over the next several weeks. Stay tuned to this VA Ag Pest Advisory for weekly updates.
Thrips numbers are increasing…’thrips season’ has begun
The following is an advisory from Ames Herbert.
Thrips species captured on sticky cards at the Tidewater AREC in Suffolk, VA, are increasing, and we expect these counts to rise for several more weeks. The adult thrips are migrating into fields from adjacent winter hosts. Counts of adult thrips have risen from about 20 per card during the second week of April to an average of 90 per card for the first week of May. The species complex consists of tobacco (mostly), eastern flower, onion, soybean, and an occasional western flower thrips (based on a subsample of 30 thrips per card). For more details on sticky card thrips captures, please see the attached graph. Sticky cards will catch all thrips species, not just the pests of cotton, therefore we also sample what is present on the cotton plant itself using soapy water thrips samples. Soapy water samples involve cutting cotton plants, submerging them in soapy water (to dislodge the thrips), vacuum filtering the sample, and counting all adult and immature thrips under a stereoscope. Soapy samples were taken on May 9 and 10 from cotton fields planted around April 20 near Boykins and Ivor, VA (cotton plants were at the 1-2 true leaf stage). Additionally, samples were taken from research plots at the Tidewater AREC that were at the 1st true leaf bud stage. In all samples, only adult thrips were present. This is important because foliar insecticide applications should target the thrips larvae which do most of the damage to seedlings. Historically, we have recommended foliar applications when the first true leaf is just expanded (1/4 inch or so). This usually coincides with the onset of larval activity. Cotton planted around April 20 is at or beyond that stage. Cotton planted a week later has not yet reached that stage (bud, only). Each year is different of course, but the many consecutive cool nights are slowing the progress of cotton and slowing the development of thrips. This may be a year to wait a few more days before making a foliar application, wait until a few more larvae are present on the plants. Thanks to my graduate student, Jessica Samler, and my assistant, Sean Malone, for taking the data used to develop this advisory and preparing the draft. Additional information: advisory-thrips-graph-docx