At a Glance
- Pests of corn, cotton, and soybeans, and can be found in peanuts and in wheat.
Stink bugs are the No. 1 pest in corn, but they are a sporadic pest that aren’t a problem in every field every year, so it is critical to understand the pest biology, when they are in the field, and when you need to be concerned about them to manage them effectively.
At the South Carolina Corn & Soybean Growers Meeting Dec. 14 at the Santee Convention Center in Santee, Clemson IPM Program assistant coordinator Tim Bryant said the two primary stink bugs to be concerned about are the brown marmorated stink bug and the Southern green stink bug.
Bryant said the brown stink bug is a native species in a large portion of the United States and has historically been considered a sporadic pest of many cultivated crops. Due to farm management practices, such as reduced tillage and no tillage, favoring large overwintering populations, and reduced use of broad-spectrum insecticides, the brown stink bug has become a perennial pest in many cases.
“These are highly mobile pests and they feed on pretty much every crop that we grow on the landscape in South Carolina,” Bryant said. “They feed on and are pests of corn, cotton, and soybeans, and can be found in peanuts and in wheat. Often times, they complete their first generation in wheat before they move into corn. Populations can build up in wheat to an economic level, and when you harvest that wheat, they will move straight into nearby corn. Often times that corn will be at a susceptible stage for injury when these types of infestations occur.
“The first time that you can see real damage is from emergence to around V6,” he said. “Stink bugs feed directly on the growing point of corn at these early stages, and when this happens, it leads to a number of different deformities and ultimately yield loss. We don’t often see high populations of stink bugs in these seedling stages. It does happen, but it is more common to see them during later stages of corn development. Seed treatments that are already applied to almost every commercial corn hybrid can help with this early injury somewhat.”
The most common injury from stink bugs in corn is in the late vegetative stages just prior to pollination and the early reproductive stages. If stink bugs are in high enough numbers during the final vegetative stages through tasseling, the corn plant will develop deformed or “banana-shaped” ears.
“It can directly impact your yield as the deformed ear will have smaller kernels and less kernels,” Bryant said. “It also opens that ear up to a number of different diseases, and secondary pests that can cause additional yield loss or grain quality concerns. Beyond that, stink bugs can still feed on ears once they get into later reproductive stages, but the direct yield loss is limited. The thing you are worried about here is grain quality issues when they feed directly on those kernels.”
Pyrethroids such as bifenthrin are effective tools for managing stink bugs, but Bryant said it is critical to apply pyrethroids at the right time. He said you need to scout for stink bugs in the field to make sure you are applying at threshold.
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