This week trapping data is not fully reported at this time, but the second generation moth flight of southwestern corn borer is really picking up in some locations (link here for latest moth trap data).

UT’s recommendation for second generation infestations of SWCB is to treat when 10% or more of plants are infested with eggs or small larvae OR when moth traps catch more than 100 moths during the previous week. However, treatment is NOT recommended if ears are already at or near the dent stage (R5). Infestations starting after R5 should cause minimal yield loss providing fields are harvested in a timely manner to avoid lodging issues. This means our earliest maturing corn should mostly escape the second generation.

Insecticides recommended for SWCB are listed in UT’s insect control recommendations for corn (link here). For second generation infestations, I prefer products that provide longer residual such as Belt, Besiege, Intrepid or Prevathon. It is more important to use longer residual insecticides in later maturing fields. These fields will be more susceptible at at risk for a longer period of time.

I should stress that corn borer population will be low in most non-Bt fields.  Blanket sprays are not justified. This stresses the need to run a few moth traps around your fields to make good management decisions.