Mixed worm populations are reportedly increasing in both South Carolina and North Carolina peanut crops.
These populations include the corn earworm (may be some tobacco budworm also, but you cannot tell these species apart without some experience and good magnification of the mandibles/jaws), beet armyworm, and fall armyworm.
Although I have not heard of worms in Virginia peanut fields, we should be on the lookout for them. With these mixed species worm complexes it will be pretty important to know which species are in your fields — so — how good are your worm ID skills?
We have a good insect ID guide available that shows the characteristics that most easily distinguish these different worm species. We will be glad to mail some to you, let us know, or you can access the guide on the web at: http://pubs.ext.vt.edu/444/444-360/444-360.html.
Knowing the species is important in choosing the right insecticide — if control is needed (see below).
The next important question is — should I treat for worms? In my experience, many growers treat fields that are not at any risk to yield loss — that is, they jump the gun. It takes a lot of leaf feeding for worms to do economic damage to peanuts, and I have seen only a handful of cases where this has occurred over the past many years.
This will be especially true this year when peanut canopies are very large, so they are able to withstand even more leaf tattering with no negative consequence.
But if you do determine that a field is in danger, feel the urge to spray, or just love killing worms, better not rely on a pyrethroid or you may not be satisfied with the results.
Corn earworms have become a little more difficult to control with pyrethroids in recent years, and beet armyworm and fall armyworm have never been very susceptible to pyrethroids.
You will need to turn to some of the non-pyrethroid options like Steward EC @9.2-11.3 oz/acres, Belt SC @2-4 oz/acre, or Blackhawk (was Tracer) @1.7-3.3 oz/acre.