Cornell Field Crops News

Timely Field Crops information for the New York Agricultural Community

Black Cutworm Moths Are Here

Jaime Cummings and Ken Wise, NYS Integrated Pest Management Program

Black cutworm moths in a pheromone trap

Black cutworm moths in a pheromone trap in Tompkins County on May 2 (photo by Jaime Cummings, NYS IPM).

Our statewide network of IPM and CCE staff, along with farmers and crop advisors set out pheromone traps for detecting migration of black cutworms (BCW) the first week of May across the state.   Not surprisingly, based on reports of BCW moths from nearby states in weeks passed, we have received reports of low numbers caught in most traps in the network (Table 1).  However, we’ve heard that some private traps out in western NY have yielded higher numbers.

Numbers of black cutworm moths in pheromone traps in the first week of May

The purpose of this pheromone trapping network is to monitor the arrival of these moths in the state so that we can establish a ‘biofix date’ to start counting growing degree days to help us know when we should expect larval damage in our fields.  Table 2 outlines BCW life cycle and activities based on accumulation of growing degree days.  Note that it takes 90 growing degree days from the time moths arrive to the time the larvae hatch, and it’s the larvae that cause the damage.  See table 3 for growing degree day calculations for select locations.

black cutworm degree daysGrowing degree days for black cutworm

Keep an eye out for BCW larvae in your fields!  And remember, the economic threshold for BCW treatment is reached when 5% or more plants in the stand have been cut or show signs of damage.  The larvae are best controlled when small (< ½”), and soil-applied insecticide rescue treatments at the time of infestation is the most economical and effective management option for BCW infestations.  Lorsban, Pounce and Warrior II all have efficacy against BCW (always consult labels for rates and instructions), and Poncho and Cruiser seed treatments are also labeled for BCW.  Spot treatment is recommended for infested areas of fields, with a 20-40’ surrounding border.  Replant may be necessary if damage is too severe to manage with insecticide.

For updates on the progress of these monitoring efforts, please subscribe to the NYS IPM Weekly Pest Report.

Black cutworm moth

Black cutworm moth (photo by Jaime Cummings, NYS IPM)

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