By Glenn Studebaker, Extension Entomologist/IPM Coordinator
We are seeing an increase in trap catches for southwestern corn borers in some areas of the state as second generation borers are beginning to emerge. Trap catches of 80 to over 100 per week are being reported in Poinsett, St. Francis and Crawford counties. Generally when numbers reach around 100 or more per trap over a one week period, we advise growers to monitor any non-Bt corn hybrids closely for southwestern corn borer or consider making an application of an insecticide with a good residual to stop second generation borers from entering the stem of the plant. Once they enter the stem it is impossible to control them. Some insecticides with a good residual are Prevathon, Besiege, Belt or Intrepid. These materials will give several weeks of control and are very effective. Consult MP144 “Insecticide Recommendations for Arkansas” for a complete list of recommended insecticides and rates. If not controlled, southwestern corn borers can cause plants to lodge later in the season, resulting in significant yield loss. It is important to note that all Bt corn hybrids give excellent control of southwestern corn borer and do not need to be treated for this pest. We are only concerned with non-Bt hybrids when addressing southwestern corn borers.