The time is now for cotton farmers to monitor stink bug populations. But University of Georgia Extension cotton entomologist Phillip Roberts pleads with growers not to apply insecticides if you do not have to. Let beneficial insects do their job, which could also help with the current whitefly outbreak.
“If you use an insecticide to kill stink bugs, you’re going to kill beneficial insects. It is what it is. Most of our important beneficials are true bugs, similar to stink bugs. Now if we have a problem with stink bugs, we need to address it. But if we don’t have a problem with stink bugs, we need to let the beneficial insects build up in our cotton and especially if you’re in an area that’s got whiteflies,” Roberts said.
“Beneficial insects are so important when we’re trying to manage whiteflies because treatments for whiteflies are very expensive. We need to try to let Mother Nature help us all she can.”
Beneficial insects, like the big-eyed bug and minute pirate bug serve as predators on insects that are cotton pests, like the corn ear worm, stink bugs and whiteflies.
It is still important, though, that cotton growers scout regularly for stink bug damage. Roberts noted that August and into the first two weeks of September are generally regarded as stink bug time in cotton. Cotton bolls are forming and are most vulnerable to damage.
“We have a lot of confidence in our thresholds that we developed for stink bugs in cotton. I probably have more confidence in that threshold than for any other pest we deal with,” Roberts said.
He said that thresholds are based on the week of bloom the cotton plant is in. The third, fourth and fifth weeks of bloom are a critical window for protection from stink bugs.
“The third, fourth and fifth week of bloom, that’s when you have the greatest number of bolls on a cotton plant which are susceptible to stink bugs. Stink bugs start to prefer to feed on bolls at maybe 12 days of age. A boll is relatively safe from stink bugs when it’s about 25 days of age,” Roberts said. “If you look at distribution and how many bolls fall within that window, the third, fourth and fifth week of bloom is the critical time to protect cotton from stink bugs.”
Roberts said most of the cotton in the state is in that window right now.