University of Missouri Extension Agronomy specialist Tim Schnakenberg found armyworms within minutes of searching the base of crops in a field in Marionville. “They are named armyworms for a reason because they take one field and they'll march to the next one,” Schnakenberg said. “This thing will grow,” Schnakenberg said about an armyworm coiled up in his hand. “If you see one you know there is more.”
Armyworms are currently invading fescue on Earl Dotson's farm near Marionville. “When you start to see these in the area, you've got some real problems,” Dotson said. “They can annihilate a crop overnight.” Fortunately for Dotson he isn't using the fescue for seed. Instead he'll use it for hay and pasture. When armyworms attack crops it can significantly impact a farmer's profit. “We've had reports of Bermuda grass eaten down to the ground so that is another concern,” Schnakenberg said. The armyworms target fescue, Bermuda grass, wheat and corn. “Every 4 or 5 years you'll see a major outbreak. Will this be a major outbreak, it's hard to tell but we are seeing quite a few and getting a lot of reports,” Schnakenberg said. “Farmers need to be out scouting looking at their fields making sure it is not above their threshold levels.”
Schnakenberg says the threshold is four per square foot. If farmers find four or more per square foot, it justifies treatment. In corn, the threshold is 25% of the plants. “There are several insecticides that could be used,” Schnakenberg said. Read more about true armyworm and treatment in the mu integrated pest and crop management newsletter at ipm.missouri.edu/ipcm/index.cfm?id=293 or in the mu extension guide at www.extension.missouri.edu/g7115.