By Glenn Studebaker, Extension Entomologist
Arkansas has seen a significant increase in conventional corn grown in the central and northern delta area of the state over the last couple of years. This increased acreage, coupled with the mild winter we just experienced, increases our chances of seeing a significant outbreak of southwestern corn borers this year. We have began catching southwestern corn borer moths in pheromone traps near Wheatley, AR this week. This is a couple of weeks earlier than our normal emergence. While many traps have relatively low numbers, St. Francis County Ag agent, Cody Griffin, reports that one trap did have over 300 moths. This is well above our threshold of 100 moths per week. Growers in this area should 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.