In the San Joaquin Valley, cotton aphids have become resistant to commonly used pesticides

Abstract

Laboratory bioassays have demonstrated that cotton aphids are resistant to organophosphate pesticides in many areas Of the Sari Joaquin Valley. Many of the aphids are resistant before they reach newly emerged cotton; their resistance tends to decline at the end of the season. The best management strategy: Avoid using pesticides in spring when they are least effective and natural enemies are abundant, and use pesticides at the end of the season to prevent sticky cotton bolls.