Large Corn Earworm Flight In Progress - Soybeans And Peanuts At Risk

From Ames Herbert, Virginia Tech Extension Entomologist

A very large movement of corn earworm moths is taking place throughout much of eastern Virginia. I did some driving throughout several counties this past Sunday nigh,t and there were so many moths flying it felt like being in a snow flurry.

Soybean and peanut fields are at very high risk to re-infestation of worms. Most fields were treated 2 weeks or more ago and are very susceptible to re-infestation.

Calls have already started coming in with growers and crop advisors seeing this re-infestation.

Here are several observations and recommendations.

• First, I think this fight is comprised mostly of corn earworm (less possibility of tobacco budworm), and I think they are coming out of our own peanut and soybean fields. Because of this, they may represent survivors from previous sprays, so there could be even higher percentages with some level of pyrethroid resistance.
   
• My advice is to try to hold off on making applications for at least a 2 or 3 more days. By waiting, the moths will lay more eggs and more small larvae will hatch.
   
• Going too early in this flight cycle may mean yet another treatment. Of course, waiting too long will allow worms to begin feeding on pods.
   
• Worm must be 3/8 inch long or longer before they can feed on pods, and remember, we base our thresholds on these sizes-not the tiny worms.
   
• When you pull the trigger, go with idea that the best kill will be achieved having a non-pyrethroid in the mix. We have gone over those options several times. The newest option added to that list is Belt by Bayer CropScience. Belt is performing very well in our field trials at 3 oz/acre. The label goes from 2-3 oz. The 2 oz rate may be enough but we have not tested it. Belt is also showing some indication that it is providing good residual activity.
   
• Consero is also new and could present another good tank mix option. Consero is a co-pack of spinosad and gamma-cyhalothrin and is labeled at 2-3 oz/acre. Other non-pyrethroid standards are Larvin, Steward, Tracer and Orthene (which should only be used if tank-mixed with a pyrethroid).