One of the most prolific and well known insect pests is the stink bug. There is a good reason for this says Kathy Flanders, Extension Specialist and professor for Auburn University and the Alabama Cooperative Extension Service. “Stink bugs have a wide range of hosts, including wheat, corn, cotton and soybeans. They can also have multiple, overlapping generations.”
Stink bugs overwinter as adults in sheltered areas, such as field borders, under tree bark or under structures such as culverts.
“In the early spring, hosts include wheat and weeds. They can also be found in greater populations on field edges, in fields that are double-cropped or in conservation tillage.”
Symptoms of stink bugs are suckering and buggy whip damage in young corn, curving or deformation of ears and scattered brown kernels.
In corn, the types of stink bugs found include the green stink bug, Southern green stink bug and the brown stink bug, which Flanders says is the hardest to kill and most cold hardy. The brown marmorated is a new pest found in Northern to mid-Alabama.
Spraying Too Late
Seed treatments, especially at higher rates, help protect early corn plants from feeding. “Products with clothianidin are better than those with thiomethoxam, which are better than imidacloprid products,” she says.
Scouting for stink bugs is difficult because they hide or will drop off the plant.
“Start scouting around V9 approximately two weeks before silking. Stalk the stink bugs by looking on plants one or two rows over instead of in the row next to you. Check several areas of the field.”
Flanders says most producers wait too late to spray to prevent stink bug damage to ears.
“Be sure to get that first spray on before tasseling. Apply an insecticide if 5 percent of plants are infested when tiny ear shoots are present. At kernel fill, treat if 10 percent of plants are infested.”
landers says producers should use a high boy sprayer, if needed, or an aerial application. Corn should not be sprayed during pollen shed or green silk.
“The worst damage is done before silking. For example, at the stage where ears are less than one inch long, if you find two stink bugs per plant, you can expect a 40-percent yield loss,” she says.