Black light trap captures of corn earworm moths greatly increased for nearly all of our reporting stations. The lowest nightly average was recorded in Petersburg (4) and our highest included Richmond County (69) and Prince George County (76). Please refer to the attached Table for more nightly averages. Additional information: blacklight-table-10-pdf

As of July 29, we have tested a total of 768 corn earworm moths in our pyrethroid AVT (adult vial testing) program. Although the percent survivorship is down somewhat from last week, we are still seeing greater than 20% survive (see the attached line graph). Could this mean that field failures are likely? Possibly, especially if worm populations are large. Our goal is to process as many moths as we can and post these weekly updates. We are also responding to calls from crop consultants, advisors and growers. We have one reported case of a ‘less than acceptable’ level of control in a peanut field. Could some of those surviving worms have been tobacco budworms, which are known to be more difficult to control with pyrethroids? Possibly, but it is almost impossible to distinguish between corn earworm and tobacco budworm without inspecting the moth parts of the worms under magnification in lab. We do know that budworms can be in the mix, up to 30% one year when we did a lot of worm IDs. Bottom line, this is the third consecutive year that local corn earworm populations are demonstrating high levels of pyrethroid resistance. Proceed with caution and consider non-pyrethroids especially in peanut or soybean fields with a lot of worms.
Additional information: cew-avt-jul-29-2010-ppt

As Dr. Herbert mentioned in his advisory, corn earworm moth captures in our network of black light traps are beginning to increase. Reports north of the James River ranged from 0 (Essex Co.) to 7 (Richmond Co./Warsaw) moths per night. In southeast Virginia, reports ranged from <2 (Petersburg) to 10 per night (Southampton Co./Courtland). Please see the attached table (pdf) for more information. Additional information: blacklight-table-10-pdf

Corn earworm moth nightly black light trap captures for 9-15 July 2010 ranged from 0.0 to 0.3 in southeast Virginia and from 0.3 to 0.8 north of the James River.

It is too early to say a lot about corn earworm, but year in and year out, this critter causes us a lot of problems. Each year we conduct a large survey of field corn in late July to get a ‘read’ on the size of the population that could move to soybean, cotton, peanut and other host crops. Although we have not done the survey, some random checks of sweet corn and field corn show from 40% to 90% infested ears. This constitutes a possible threat. Earworms are worse in dry years as fewer are killed by rain (can drown pupae before they mature, can wash eggs from plants, can increase the incidence on fungal worm diseases, etc.). The other ‘shoe to drop’ is the issue with pyrethroid resistance. In the last two years (2008 and 2009) we found a large increase in the number of moths that survived in our pyrethroid vial testing program (from less than 5-10% survivors prior to 2008, to 20-40% survivors in 2008 and 2009). So far this year we have tested a total of 235 moths from May 27 to the present. The % survivorship has fluctuated, as is normal, starting at 13%, then to 12%, to 7%, to 25% in last week’s sample. Granted these results are from a small number of moths, but all indications are that we may need to address use of pyrethroids again this summer. We will keep posting the information.

Because of this continuing hot, dry weather, we are not seeing a lot of insect activity in cotton, peanuts or soybeans. There are a few exceptions. Grasshoppers are doing some damage to soybeans in certain areas. Spider mites are starting to show up in most crops, but so far, the buildup is pretty gradual. Finally, there is some hope this Saturday for some decent amounts of rainfall for a lot of the area. If we miss that opportunity&& Potato leafhoppers are showing up in peanuts, but again, the buildup is gradual. We are just beginning to get a picture of how the 2010 corn earworm population is developing. We may be in for some problems (see the Corn earworm update), again, if the weather doesn’t turn around with more frequent rains. PS, if we could shoot about ½ million deer we would solve a lot of our ‘pest’ problems, at least for many of our soybean growers.

The nightly average number of corn earworm moths captured in our black light traps has been low so far for the 2010 season, only about 0.1 per night.

Please join us July 14th in Painter, VA for the 2010 Eastern Shore AREC Annual Research Field Day. The field program will begin at 8:30 am and there will be a lunch following the tours. Click More News to view a draft of the program.
Hope to see you there. Additional information: 2010-esarec-field-day-program-1july2010-docx