Moth traps (see Quick Links menu) indicated a small upswing in catches of southwestern corn borer moths this past week.  Expect a much sharper increase in some areas next week as the second generation really kicks off.  The reality is that the vast majority of non-Bt fields in the state will not have substantial corn borer infestations.  But some non-Bt corn fields will be at risk.  Below are some points to consider if you are in an area with chronic SWCB problems or moth trapping during the first generation indicated the potential for problems in your area.

• During the second generation, a weekly moth trap catch of 50 moths per week typically indicates a low to moderate risk for yield loss.
• Traps catches of 100 moths per week suggests a higher risk for yield loss in at least some nearby fields of non-Bt corn.
• Averaging 200 or more moths per week indicate a high risk of substantial yield loss for non-Bt fields in that area.  These levels should often trigger an insecticide application to fields that are still susceptible to injury.

Corn gets less susceptible as it matures.  Late maturing fields will be far more susceptible than those that are already at the milk stage (R3) or further developed. The threat of yield loss from new infestations is minimal by the time dent (R5) is reached.

• In high risk scenarios, consider timing an insecticide application to coincide with the first big upswing of moth catches.

There are a number of insecticides recommended for control of corn borers including Belt, Besiege, Intrepid, Prevathon, and several synthetic pyrethroids.  Recommended rates can be found in the UT Insect Control Recommendations for Corn.  Although cheaper, the synthetic pyrethroids just don’t have the residual control typically needed to provide the necessary control of sustained infestations of SWCB.