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.
Category Archives: Insect
Brown marmorated stink bug black light trap catches for the week ending July 28, 2011
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
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
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
Corn earworm pheromone trap catch for the Northern Neck of Virginia – Last week of July
Handy Bt Trait Table: Midwest corn hybrids
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
Results of the 2011 corn earworm moth field corn survey
Please click “More” to see Ames Herbert’s annual field corn survey for predicting corn earworm activity in other crops. Additional information: cewsurvey2011-pdf
Brown marmorated stink bug black light trap catches for the week ending July 21, 2011
Brown marmorated stink bug (BMSB) black light trap catches for this week totaled 33 in Studley/Mechanicsville, 65 in Petersburg, 2 in Warsaw, 2 in Painter, and 59 in Virginia Beach. No BMSB were caught in Southampton, Prince George, 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 21, 2011
Corn earworm moth black light trap catches remain low, with a range of 0.1 to 3.6 per night. Please click “More” to see the black light data table. In 2010, trap catch numbers began their upward climb during the last week of July. Also, Helene Doughty reported that pheromone traps in Pungo captured a weekly total of 2 corn earworm moths at the Baker farm (the Henley farm trap was damaged). Eleven corn earworm moths were captured in the Hampton Roads AREC pheromone trap in Virginia Beach, and 9 were caught in the Eastern Shore AREC pheromone trap last week. Additional information: blacklight-table-11-pdf
Heavy corn earworm activity in the Northern Neck of Virginia and summary of insecticide work in sweet corn
Based on pheromone moth traps monitored by Rafe Parker from Parker Farms, Oak Grove, Va, corn earworm moth activity has picked up significantly in the Northern Neck Region of Virginia. Counts jumped from less than 10 for past 2 weeks to about 100 moths this week. these moths will be flying to sweet corn, soybeans, cotton, green beans, and tomatoes among other crops. Be on the lookout for the eggs and small larvae of this pest, or begin the preventative spray programs. There are a wide range of effective insecticides for this pest. Sweet corn is probably the most difficult crop to achieve effective control of corn earworm because very few insecticides kill the eggs, eggs develop and hatch quickly in the summer heat, and larvae move down the silks and into ears where they are protected. Click More to view a summary of recent insecticide trials performed on sweet corn in Eastern Virginia.
Additional information: kuharsweetcorn-ipm-handout-2010-doc