Producers throughout the state need to remain vigilant regarding the movement of stalk borers into cornfields. Robert Scott, Illinois State Water Survey, has provided Figure 2 that reveals the number of heat-unit accumulations (base 41°F) from January 1 to May 22. Stalk borers begin moving into corn when 1,100 heat units have accumulated. This suggests that initial movement across the northern one-third of the state was under way at least by May 22. For the southern one-third of the state, as of May 22, about 50% of the stalk borer movement into corn had already taken place (1,400 to 1,700 heat-unit accumulations). As Kevin Steffey indicated last week, we recommend scouting when 1,300 to 1,400 heat units have accumulated, and a decision to treat with an insecticide should be made between 1,400 to 1,700 heat units. For the full stalk borer "story" take a look at issue 7 of this Bulletin.--Mike Gray |
Injury to plants at edge of cornfield caused by stalk borers.
Stalk borer larva.
Injury to corn plant caused by stalk borer.