Research HighlightsAssessing Stink Bug Strategies
In this article, you’ll find details on:
- Farmers have limited insecticide options for stink bug control, an annual challenge for mid-Gulf Coast soybeans in Texas and many other regions.
- Understanding specific species in the stink bug complex found in a field guides treatment decisions.
- Soybean planting timing can help manage stink bug pressure.
By Laura Temple
Stink bugs feed on soybeans as they develop in their pods, reducing crop quality. That leads to quality dockages when selling the crop.
“Controlling stink bugs is the main insect challenge in soybeans grown in South Texas,” explains Stephen Biles, an integrated pest management extension agent for Texas A&M AgriLife Extension Service. “It doesn’t take much damage to cause profit losses.”
He has been monitoring stink bug pressure and evaluating control options with support from the Texas Soybean Board. Brown, green and red-banded stink bugs comprise the bulk of the stink bug complex in this area, and area soybean farmers usually spray them at least once each year.
Confirmed economic thresholds help farmers determine when they should treat, but Biles says that how they treat should depend on the stink bug populations present in a field.
“Soybeans can tolerate just one-third of the pressure from red-banded stink bugs compared to other species,” he reports. “They cause more damage and seed discoloration, though we aren’t sure why.”
The sweep net thresholds for treatment are 36 green and brown stink bugs per 100 sweeps, and just 16 red-banded stink bugs per 100 sweeps. He notes that similar thresholds have been established for those who prefer to scout with drop cloths. Stink bugs don’t run away when shaken onto a cloth, so scouts get reliable population counts with this method as well.
Insecticide Options
Biles says farmers have limited insecticide options for stink bugs. Pyrethroids control green stink bugs effectively, but both brown and red-banded stink bugs have developed resistance to this chemistry. Acephate serves as an effective alternative for most stink bug populations. Bifenthrin mixed with imidacloprid or acephate provides additional modes of action.
“If we keep using the same thing to control stink bugs, we are asking for resistance,” he says.
For field populations with a majority of green stink bugs, he recommends applying a pyrethroid, which is the most cost-efficient option. However, if a field mainly has red-banded stink bugs, he recommends acephate, as he has seen pyrethroids fail in those cases.
Biles says that the three to four generations of stink bugs that occur every year eventually overlap so that all growth stages can be found in the field at once. Pyrethroids and acephate provide control throughout the life cycle.
“After treatment, fields need to be scouted two days later to confirm the level of control,” he adds.
Integrated Pest Management Tactics
The stink bug complex in a given field changes from year to year, depending on factors that impact overwintering and early season development. Uncontrollable dynamics like harsh winters, timely spring rains or higher than average populations of predators like assassin bugs can affect green, brown and red-banded stink bugs differently.
Soybean planting date is a more controllable practice that can help manage stink bug pressure.
“Soybeans planted in March usually need just one insecticide application,” Biles reports. “For soybeans planted in early April, farmers should budget for two insecticide applications. Fields planted later will likely need three or four sprays.”
He acknowledges that very wet or very dry springs create challenges for planting timing. While managing soybeans based on spring weather conditions, farmers can at least estimate the need for stink bug control as the soybeans mature.
“Most farmers and consultants scout fields weekly,” he says. “When they start picking up stink bugs, they should consider scouting more often.”
Additional Resources
- Monitoring and Managing Stink Bugs in Texas – SRIN article
- Stink Bugs – SRIN information page
- Evaluating Profitable Stink Bug Thresholds and Treatment Timing – SRIN article
Published: Dec 2, 2024
The materials on SRIN were funded with checkoff dollars from United Soybean Board and the North Central Soybean Research Program. To find checkoff funded research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.
