This has been an active year for stink bugs, with green stink bug as the predominant pest species across the Commonwealth. However, depending on crop and location, brown and brown marmorated stink bugs have also been at economic levels. Within the next few weeks, stink bug numbers should gradually decline in some crops, while nymphs will continue to develop on others.
Soybean producers should monitor their fields for stink bugs (Figure 1), keeping in mind that levels on the edges of fields are not representative of field centers. There is a strong field margin effect with stink bugs; field centers generally have lower levels than field edges that border wood lots or other stink bug sources.
Stink bugs damage soybeans in two ways:
(1) By feeding on pods, stink bugs reduce yield and quality of plants.
(2) Excessive feeding on soybeans can cause a ‘stay-green’ effect; it takes much longer for affected plants to senesce in fall. This stay-green effect can be very apparent on field margins.
The threshold for stink bugs is 9 per 25 sweeps when plants reach the R3 stage.
Green, brown, and brown marmorated stink bugs have also been common on various vegetable crops, including tomatoes, peppers, sweet corn, green beans, okra, and eggplant. Fruit and pod feeding can reduce produce quality severely. With tomatoes and peppers, fruit damage is recognized by surface spots that don’t color properly as fruit ripens (Figure 2). Underneath the skin, the damaged area appears corky. Stink bugs feed through the husk leaves on sweet corn, resulting in shriveled and discolored kernels. Stink bug damage to green beans appears as sunken areas on pods.
Generally, most pyrethroid insecticides work well against green stink bugs. For brown and brown marmorated stink bugs, insecticide sprays containing bifenthrin, cyfluthrin, and dinotefuran can be effective.
Producers with flowering crops need to follow label guidelines to protect pollinators. Spraying after 6:00 PM can reduce honey bee exposure to sprays. Some insecticide labels, such as those containing dinotefuran, may require notification of nearby beekeepers when sprayed on fields being worked by pollinators.
By Ric Bessin, Extension Entomologist