We have seen a significant increase in southwestern corn borer moths in pheromone traps in Monroe and Woodruff Counties this week. Traps in south Woodruff county near Cotton Plant are catching over 100 moths per trap. Northern Monroe county is seeing some traps hitting near 300 moths in the area that had high infestations last year. Growers in these areas 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 achieve control with a foliar insecticide. The following insecticides have good residual activity:
Prevathon 14 to 20 oz/acre
Besiege 8 to 10 oz/acre
Intrepid 4 to 16 oz/acre
Intrepid Edge 4 to 12 oz/acre
Higher rates generally will give a longer residual. Consult MP144 “Insecticide Recommendations for Arkansas” for a complete list of recommended insecticides and rates. Most of the other products listed have much shorter residual activity (3-4 days) and will need to be applied close to egg hatch if used. Getting good coverage is also important. Now is not the time to skimp on application volume. 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. Other areas of the state are not experiencing high numbers at this time and should be safe from economic damage from this pest. The latest trap catches by county can be seen here Southwestern Corn Borer Trap Catch Report 6-22-2018.
“This work is supported by the Crop Protection and Pest Management Program [grant no. 2017-70006-27279/project accession no. 1013890] from the USDA National Institute of Food and Agriculture.”