When it comes to managing insects in cotton, corn and soybeans, Dominic Reisig strongly encourages farmers, particularly cotton farmers, to invest in a professional consultant to scout their crops.
“If a farmer wants to manage plant bugs well, they probably need to hire a consultant. It’s just really intense the kind of sampling you have to do. Here in northeastern North Carolina, where the plant bug pressure can be really intense, it would not be uncommon for someone to have to spray six times for plant bugs. The frequency you need to scout and do a good job is at least once a week and depending on the field and growing conditions, it might even be twice a week,” said Dominic Reisig, North Carolina State University Extension entomologist
Most of the insect problems are in cotton now, although stink bugs are still a challenge in corn and soybeans while Southern corn billbugs are an issue for some corn farmers in North Carolina. Reisig says thrips are a never-ending challenge for cotton farmers, but the good news is they can be effectively managed.
“I feel we have a good handle on thrips, even though we have some resistance issues. We have some tools to help growers better time sprays. We understand the system better. Next year, the new trait from Bayer, Thyrvon, will be available. That should help out a lot,” he says.
Plant bugs not going away
Plant bugs on the other hand are a problem that is not going away in cotton. Reisig says plant bugs are now expanding their range from northeastern North Carolina and are now moving west and south, even to South Carolina, where they have not been an issue in the past.
Reisig notes that when corn dries down, it can be a source of plant bugs that move on to cotton, but the plant bugs do not economically damage corn or soybeans in North Carolina. In northeastern North Carolina there is also limited acreage of Irish potatoes and clary sage that are both sources of plant bugs.
“Plant bugs are expanding for reasons we can’t explain. They are piercing sucking insects like stink bugs. They are small and really mobile. They can fly into your fields quickly and lay they eggs, and those little tiny nymphs like to feed on the square the developing floral bud of cotton. And when they feed on that the plant responds to that by abscising the tissue, so your square falls off, so you don’t get a bloom, you don’t get a boll,” Reisig explains.
“For us they plant bugs tend to do the most damage in pre-blooming cotton. They are taking out that square before it can bloom. Because cotton blooms for a long time, they can be damaging later as well,” he says.
The good news is plant bugs can be controlled. Reisig says there are good insecticide tools available to farmers, but it comes down to knowing where the pests are and the only way to know that is to scout and treat. “We have products that control the insects. We have ways to find the insects. We know how to do it. We know the thresholds; we know the products to treat them.”
Reisig says insecticide resistance is an issue just like herbicide resistance for the exact same reason: Over reliance on a single product. “I think the advantage we have in the insect world is we have an available suite of products that can still fit in the system. It seems like in the herbicide world, they are just one step away from being completely broken.”
“The one that concerns me is bollworm in cotton. We are relying on a single Bt trait to control it. We are relying on a single foliar insecticide to control it. That’s the closest thing we have to herbicide resistance. One tactic we are taking in North Carolina is to try to limit the use in other crops. In soybeans we recommend growers not use the active ingredient chlorantraniliprole, that’s in Exirel, Prevathon (now called Vantacor) and Besiege, because we have other products that will kill worms in soybeans and we need chlorantraniliprole in cotton, ” Reisig says.
About the Author(s)
You May Also Like