Bean Binoculars Incident

This soybean field was scouted at the R7 (beginning maturity) growth stage and intensive defoliation was observed in widespread areas across the field. This injury was confirmed by a NC State Extension Specialist as damage from Mexican Bean Beetles. Larvae and adults will feed on all parts of the plant, but injury is generally most severe on the foliage. Mexican bean beetles feed on the underside of the leaf and because of this patchy yellow and brown areas can often be visible on the tops of injured leaves. Individual plants were 25-50% defoliated and damage was present across ~50% of the site.

The economic threshold in North Carolina for Mexican Bean Beetle is 15% defoliation throughout the canopy between the flowering and pod fill stages. Recommended treatment to control this pest includes applying a pyrethroid insecticide and recommended insecticides can be found here in the North Carolina Agricultural Chemicals Manual.