Please click “More” for the corn earworm moth and brown marmorated stink bug tables. Corn earworm moth numbers varied greatly by location, with some very high captures in Charles City. Brown marmorated stink bug numbers ranged from zero to 2.4 per night. Thanks to the following for their reports this week: David Moore, John Allison, Laura Maxey, Mary Beahm, Keith Balderson, Scott Reiter, Kelvin Wells, Mark Kraemer, Ames Herbert and crew, and Helene Doughty. Additional information: blt29aug13-pdf

Please click “More” to view the average nightly black light trap captures of corn earworm moths and brown marmorated stink bugs (BMSB). This week’s corn earworm catches ranged from 0.1 to 5.1 per night; BMSB ranged from zero to 1.9 per night. Thanks to our trap operators Chris Drake, Keith Balderson, Mary Beahm, Mark Kraemer, Mike Parrish, Ames Herbert and crew, Laura Maxey, and Jim Jenrette for their reports this week. Also, thanks to all those providing a location and power source for these traps. Additional information: blt-aug22-pdf

As of August 22, 2013, we have evaluated 545 Helicoverpa zea moths (=corn earworm) (=bollworm) in our cypermethrin vial tests (cypermethrin is a standard pyrethroid). Results are provided in the attached pdf document (please click “More”). In the vial test, moths are exposed to cypermethrin for 24 hours and are then rated as dead, down, or alive. For the entire season to date, an average of 22% of H. zea moths have survived the test. Please refer to Dr. Herbert’s August 13th advisory for how to best interpret these vial test results. Additional information: cypermethrin-pdf

Please click “More” for this week’s black light trap catches of corn earworm moths and brown marmorated stink bugs. Thanks to all of our trap operators for their reports! Additional information: blt-15-aug-2013-pdf

CEW moth activity is definitely beginning to increase. We are now catching 20-30 per night in our traps compared to 4 or 5 per night last week. We are not sure how this will progress. A lot will depend on the weather, and eventually, corn harvest. We will keep posting updates.
PEANUTS: We are beginning to find just a few worms in peanut fields—way below any reasonable threshold (See the advisory I posted on the peanut/worm situation for more details).
SORGHUM: A few worms are beginning to show up in sorghum heads (See the advisory I posted on sorghum head worms).
SOYBEAN: We are getting reports of a few worms in soybean fields but not at threshold levels, and not threatening the seed.
COTTON: Although we have found a few CEW eggs, we are finding almost no worms. This could be year when the BG2 and WideStrike provide enough protection, without additional foliar sprays.
PYRETHROID RESISTANCE: Keep in mind that I use the term ‘resistance’ loosely. We cannot prove/disprove actual resistance using the AVT (Adult Vial Testing) method, only determine the percent that survive the pyrethroid challenge. So, where do we stand this year? If you open the file (‘more’ button) you can get a quick comparison of where we are compared to last year—so far we are seeing only about 30% survivorship. But also notice that the number of moths tested to date is very low, which could bias our results. Is 30% survivorship enough to warrant a shift to a non-pyrethroid—my answer is, it depends. My rule of thumb is—if a field is at or just above the threshold (check that for each crop), a pyrethroid applied at the highest labeled rate, using a spray system that achieves good plant coverage, will do well. But, if a field is 3 to 4 times the threshold, or higher, a non-pyrethroid will be needed.
Additional information: cew-avt-results-aug-13-pptx

As of this week, we are starting to find a few corn earworms in sorghum grain heads. We suggest that you should begin sampling any sorghum fields that have heads entering the milk stage—and many in Virginia are in that stage. Using the ‘bucket/shake’ method is the best way to determine the average number of worms per head. We recommend doing a series of 10-head samples in each field. Shake 10 randomly selected heads into a white 5-gallon bucket and count the worms/10=average per head. Do several 10-head samples in each field taking samples from areas with any obvious differences (different head maturities, areas next to corn, etc.)—then calculate an overall worm/head field average. Recommendations are pretty variable across states, but an average of 2 worms per head, or more, should trigger a spray. Use a spray boom/nozzle/gpa/psi system that delivers as much product to the heads as possible. Spraying leaves is a waste of product—the more product hitting the heads, the better. Directing sprays to the heads is even more important in varieties with compact heads (vs loose heads). When heads are compact, worms tend to burrow to the center, are not easily seen, and are not as vulnerable to sprays. Remember, the insecticides used for worm control depend on direct contact.

What insecticides should you use? Sorghum has fewer labeled insecticides than many commodities, but there is a pretty good selection with different modes-of-action. Pyrethroids include Tombstone, Mustang Maxx, Karate/Warrior, and Asana XL, and others. Non-pyrethroids include Belt, Blackhawk (was Tracer), and Lannate. There are a few others that combine active ingredients like Stallion (Mustang + Lorsban) and Consero (Prolex + Tracer). Note that we have not evaluated these products so cannot make comments about control, but have experienced lack of control with pyrethroids, alone, when worm populations were high or worms were a large size (harder to kill) when sprays were applied.