Scouting Time For Black Cutworm Damage

 

 

Our Black Cutworm Monitoring Network detected eight areas around the state where moths were heavy enough to be concerned about potential damage from cutworm caterpillars. Therefore, corn fields in these areas should receive scouting attention. But remember that we do not have traps everywhere, and growers should be generally aware of this elevated risk and scout their fields. Three of the eight sites have exceeded 300 degree days since their significant flights, so as we reported last week, scouting for cutting damage in the southern part of the state scouting should have already started (Table 1). The remaining sites around the state range from 189-283 degree days, so scouting for the damage should occur in the coming days (Table 1).

 

Because caterpillar populations are notoriously spotty, I would not recommend using the elevated risk as a justification for adding insecticide to a tank mix unless you have confirmed that damage exceeds the economic threshold. Insecticide applications not targeted and timed appropriately will not be effective, and will probably waste money. While some Bt varieties can be helpful for managing black cutworm, seed treatments are not very effective. Rescue treatments are usually the most efficient and economical tactic for managing black cutworm. For more information, see our Penn State Extension factsheet.

 

Table 1. Degree-day accumulations through 30 May 2016 in eight regions in Pennsylvania that experienced significant flights of black cutworm moths. When 300 degree days accumulate at each site from the day of the flights, cutting damage can be expected to be evident in fields—this is when scouting should occur.