Stink bugs are a common pest problem in cotton fields across the South. Feeding stink bugs increase lint staining, cause boll abscission, help transmit boll rot pathogens and reduce yields and overall lint quality. An insect pest that will reduce the bottom line of profit potential will command producers’ attention.
“Stink bugs are by far the most common insect we are going to need to spray,” says Phillip Roberts, University of Georgia Extension entomologist.
The problem is that stink bugs are not all that’s out in the cotton field; there are plenty of other insects, both beneficial and not, in the field.
What’s In Your Field?
“Southern green stink bug is the most common species in Georgia, with three to four generations per year,” says Michael Toews, University of Georgia entomologist.
But, it is a buildup of brown stink bugs in the last few years that has made knowing what species you have more important.
“If you have brown stink bugs in the mix, which has been more than 50 percent of our species composition, they are tolerant to pyrethroid insecticides,” Toews says. “For the brown stink bugs, you are going to need an organophosphate insecticide application.
“With this,” he says, “producers run the risk of a secondary pest outbreak like spider mites or aphids, and you wipe out natural enemies.”
Treatment Pros and Cons
Roberts says he tries to get producers to think about what else is inthe field.
“The presence of those insects – spider mites, aphids and whiteflies – can influence decisions when targeting stink bugs,” he says. “Producers should think of the ‘big picture’ and try not to do anything that will aggravate these other pests.”
Through research, entomologists have learned that stink bugs move from crop-to-crop but do not move into the interior of the field as often.
“When stink bugs move, they are not likely to move far into an adjacent field,” Toews says. “They are not moving far into the field; they move and stop in the edges.”
Knowing this and also trying to think “big picture” on insect management, Toews says it prompted the question, “Does it make sense to spray the entire field or does it make more sense to spray around the edges?”
On The Edge
Toews says he has looked at treating just the border area of fields for the last four years and has found that this is a viable option
“In the case where we do border sprays, we tend to get our two border sprays down, and it buys us about three weeks,” he says. “Then we might need an application about the fifth week of bloom, if we need it at all.”
Toews says about half the time another spray is needed and the other half, it isn’t.
“In these studies, we reached 30 to 40 feet into the field from the edge,” he says. “We applied four ounces of Bidrin, plus two ounces of Baythroid XL. One application was made in the first week of bloom and another application in the second week of bloom. Border sprays were not based on a threshold.”
Their studies were on smaller fields initially, but Toews says in smaller fields stink bugs will get across the field faster, and the whole field will act as a border.
“In bigger fields, which is why we went to 60-acre fields in our tests, it makes much more of a difference,” he says.
Toews says whole field applications are effective but require more time and insecticide, which means more money.
“Growers should consider early season border applications, which appear to provide stink bug suppression for about three weeks,” he says. “In light years, this may be all that is required.
“Border sprays are not killing all the natural enemies, and it saves time and active ingredient. It is insecticide savings.”
Contact Amanda Huber at (352) 486-7006 or firstname.lastname@example.org.
Benefit of Border Sprays
• Saves time and money.
• Helps preserve beneficial insects.
• Are not based on a threshold.
• Stink bugs may be on field edges.
• Has more impact on larger fields.