The Stalk Borer Watch Continues

May 21, 1999
In last week's Bulletin (issue no. 8, May 14, 1999), Mike Gray offered the opening salvo of information about stalk borers and the threat they pose to corn. After discussing their biology and appearance and the injury they cause, he provided information about tracking their movement by accumulating heat units above a base temperature of 41°F. An update on accumulated heat units is provided in Figure 2, which shows heat-unit accumulations from January 1 through May 17. Stalk borers first begin to move into corn when 1,100 heat units accumulate; 50 percent movement occurs when about 1,400 to 1,700 heat units accumulate. The map in Figure 2 suggests that movement into border rows of corn could have begun anywhere in the southern one-third of the state. We recommend scouting for stalk borers when about 1,300 to 1,400 heat units have accumulated, so everyone south of I-70 should be alert for early signs of stalk borer injury.

Insecticides for stalk borer control were published in last week's issue of the Bulletin (issue no. 8, May 14, 1999). Remember, these insecticides will be effective only if they contact larvae during their movement from plant to plant and while the larvae are relatively small. After the stalk borers bore into the plants, they are difficult to control. Timing is everything.--Kevin Steffey

Author: Kevin Steffey