Category Archives: Commodity

Caterpiller and spider mite control decisions in peanut, Ames Herbert and Rick Brandenburg

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Early August is the time of year we commonly see populations of corn earworms and other caterpillars in peanuts in Virginia and North Carolina. Recent light trap catches would indicate we should see some worms in peanut over the next couple of weeks. Two very appropriate questions have been asked in recent weeks and a quick review of possible answers to these questions is in order.

The first question focuses on the issue of insecticide resistance in corn earworm populations in peanuts. There is some indication that pyrethroid resistance among corn earworms, including the ones we find in peanut fields, is a real concern. However, the pyrethroids cost less than other options and for many growers are the preferred means of control. In addition, pyrethroids are not the best choice for controlling tobacco budworms or fall armyworms in peanuts and control is often less than satisfactory against these pests. The second question focuses on which product to select if the field is also infested with spider mites.

In our opinion, 100% control should not be an overriding goal when treating for caterpillars in peanuts. Good control of corn earworm can still be obtained in most situations with the high rate of pyrethroids. Guidelines for helping determine which type of product to select in peanuts this year might include the following:

1.Very high populations of worms. If populations exceed 8-10 worms per row foot, then the use of a non-pyrethroid insecticide might be a better choice.

2.If populations of tobacco budworm or fall armyworm make up more than 25% of the population, then the use of a non-pyrethroid insecticide might be a better choice.

3.If you understand that you do not need to obtain 100% control of caterpillars to preserve yield, then the use of a non-pyrethroid insecticide might be a better choice.

4.If spider mites are present, then Danitol or Brigade should be used for caterpillar control.

Guidelines are subject to specific local conditions, but in general we believe that pyrethroids still hold value for caterpillar control in peanuts this year. The recent rains certainly helped with the spider mite situation, but temperatures this week will drive populations back up. If caterpillar and/or spider mite populations increase in the coming weeks, we will update you on any changes in our recommendations.

Cotton insect pest update

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The corn earworm (bollworm) flight out of corn started over the past weekend. A few cotton fields have reached what we use as the egg threshold in conventional varieties (10 eggs in 100 terminals). Our long-standing recommendation is to treat BGll and Widestrike varieties with a single application of the pyrethroid of choice at the highest labeled rate, 5 to 7 days after the egg threshold. In most areas, that should happen next week. Even with the potential for corn earworm/bollworm pyrethroid resistance/tolerance (see the other July 28 advisory), I think a high rate of pyrethroid is still a good choice for cotton, as it has performed very well in past years. The difference compared with soybean (where we do recommend non-pyrethroids) is that in cotton, we only have to control the few worms that have escaped the Bollgard/Widestrike insect toxins. Are these escapes easier to control because they have been exposed to the Bt toxins? There are also some stink bug hangers-on in some fields, and we are seeing a shift from predominantly brown stink bugs to predominately green stink bugs, which are easily controlled with normal pyrethroids. So, for the money, consider a single high rate treatment of your pyrethroid of choice. There is a lot of confusion about some of the pyrethroid products, especially those combining bifenthrin and zeta-cypermethrin (e.g., Steed, Hero). We have attached a table that provides the amounts of active ingredient of each insecticide, for the recommended lowest and highest labeled rates for cotton bollworm/stink bug contorl. In general, you can get more active ingredient per acre if you fall back to the single-insecticide products (e.g., Brigade, Mustang). Additional information: hero-steed-mustang-brigade-table-july-28-2011-docx

Soybean insect pest update: corn earworm and stink bugs

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Corn earworm moths are beginning to migrate from corn fields and levels of pyrethroid survivorship are extremely high (see other advisory posted on July 28). Corn earworm populations are always worse in dry years. But we have had some recent rains over much of Virginia so we may see some benefit from those. Corn earworm moths are already laying eggs in cotton, so likely they are also laying eggs in soybean fields. They would be attracted to flowering fields and those with younger pods. A lot of our crop is in these growth stages. I would recommend beginning to scout soybean fields by next week in the southern counties, and by the middle of the following week in middle and northern counties. How will this problem develop over the next few weeks, only time will tell?
Although stink bugs are present in some soybean fields, the numbers are still low. We are seeing a shift from primarily brown stink bugs to primarily green stink bugs, which is the norm for this time of year in Virginia. Fortunately, green stink bugs are easy to control with pyrethroids, and when browns comprise 30% or less of the total (which is the norm), we also see good control. Although brown marmorated stink bugs are being reported in some locations in Virginia, so far, none have invaded soybeans, and this is also true for Maryland. We will begin a large scale soybean monitoring effort next week (Aug 1).
What are our current recommendations for controlling soybean insects? Because of the potential for corn earworm pyrethroid resistance/tolerance, consider a non-pyrethroid insecticide option, especially if worm counts are high (more than 3 times the threshold). If stink bugs are also present in economic levels, a pyrethroid or neonicotinoid insecticide would need to be added as most of the non-pyrethroid worm control options do not provide stink bug control. Another option that has a good track record both here and in the Delta states is a tank mix of one-half pound of Orthene (Acephate) plus a high rate of pyrethroid. For reasons we don’t fully understand, this tank mix is doing a very good job in controlling corn earworms, tobacco budworms, and stink bugs.

Brown marmorated stink bug black light trap catches for the week ending July 28, 2011

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Brown marmorated stink bug (BMSB) black light trap catches for this week totaled 50 in Studley/Mechanicsville, 151 in Petersburg, 12 in Warsaw, 63 in Virginia Beach, and 3 in each of the two traps in Prince George. No BMSB were caught in Chesapeake, Painter, Southampton, Prince George, Isle of Wight, or Suffolk black light traps. Please click “More” for the data table. Additional information: bmsb-blacklight-table-11-pdf

Corn earworm moth trap captures for the week ending July 28, 2011

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The flight of corn earworm moths out of corn has begun and black light trap catches are on the rise. Please click “More” to see the current black light data table. Pheromone traps in Virginia Beach captured a weekly total of 4 corn earworm moths at the Baker farm, 24 at the Henley farm, and 31 at the Hampton Roads AREC. Six were caught in the Eastern Shore AREC pheromone trap. Thanks to the following for their reports this week: Mary Beahm, Neil Clark, Mark Kraemer, Scott Reiter, Kelvin Wells, Watson Lawrence, Helene Doughty, Laura Maxey, Janet Spencer, David Moore, and the Tidewater AREC entomology crew. Additional information: blacklight-table-11-pdf

Corn earworm pyrethroid vials tests show very high levels of survivorship

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Corn earworm moth counts in local black light traps have increased from a few per night to 40-50 per night. These are not large numbers, but do indicate that moths are beginning to emerge from corn fields. Moths from corn are the second generation that migrates into soybean, cotton and peanut fields. We have run two batches of these second generation moths in our pyrethroid vial testing program with alarming results….55% (330 tested) and 59% (131 tested) survivorship for the July 26th and 27th samples (see the attached line graph). These are unprecedented levels for Virginia where in recent years, 40% survivorship was considered high. In a conversation with Dr. Rogers Leonard, a field crops entomologist at LSU, he confirmed that they are seeing even higher levels of survivorship in the Delta states and are dealing with extremely large corn earworm/tobacco budworm infestations in soybean. See more comments relating to soybean and cotton in the other July 28 advisories.
Additional information: cew-avt-graphs-july-28-2011-pptx

VT Tidewater AREC Pre-Harvest Field Tour–September 15, 2011

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The Virginia Tech Tidewater Agricultural Research and Extension Center (AREC) will hold its pre-harvest field crops tour the morning of Thursday, September 15th. The tour will be held at the Center’s research farm at 1045 Hare Road in Suffolk. Specialists will display field research in progress and present valuable information for the 2011 harvest season and 2012 planting season. Important topics addressed will include cotton defoliation strategies; peanut variety and maturity assessment; cover crop establishment; variety evaluation in cotton, corn and grain sorghum; and disease and insect management in cotton, peanut, and soybean, including adaptation to the pending loss of Aldicarb (Temik®) nematicide-insecticide. Virginia private pesticide applicator certification credits will be available for participants. Lunch will be served after the tour and updates presented from USDA Farm Service Agency (FSA) and Natural Resource Conservation Service (NRCS).

Registration begins at 8:30 a.m. with the tour starting promptly at 9:00 a.m. Pre-registration by September 7th is highly encouraged by contacting Gail White at the Tidewater AREC (757-657-6450, ext. 430 or guwhite@vt.edu). If you are a person with a disability and desire any assistive devices, services or other accommodations to participate in this activity, please contact the Tidewater Agricultural Research and Extension Center at 757-657-6450 (TDD number is 800-828-1120) during business hours of 8 am and 4:30 pm to discuss accommodations five days prior to the event.

Handy Bt Trait Table: Midwest corn hybrids

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This came across my desk the other day, and I hope you find it as useful as I have. The “Handy Bt Trait Table”, by Chris DiFonzo, Michigan State University, and Eileen Cullen, University of Wisconsin, has a great summary table for MidWest hybrids. The table lists the traits currently available (last updated Feb. 2011), insects controlled, and refuge size per trait. The table does not address refuge information for corn planted in cotton designated counties. That information can be obtained by checking with your supplier and/or reviewing the product use guide. Additional information: cornbttraittable-difonzo-and-cullen-2011-pdf