2016 University of Minnesota Cooperative Black Cutworm Trapping Network Report #2

Weeks of March 19 - March 25, 2016 and March 26 - April 1, 2016

This newsletter is available in a print-friendly pdf format: 2016 Black Cutworm Network Issue 2

BCW 2016-02 Map

We once again have a good crew of cooperators monitoring the migration of black cutworm moths into Minnesota. Black cutworm pheromone traps are checked daily and we will try to have the previous weeks results posted each Thursday.

Damage from black cutworm infestations can be predicted, in part, from sex pheromone trap captures and degree-day accumulations. We consider a trap capture of 8 or more moths over a two night period as an indicator of risk for larval damage to corn and other crops later.

Early this spring, 2016 weather systems were not been favorable for bringing cutworms into MN.  This changed late last week as a trap in Swift County had 8 black cutworm moths the morning of the March 28th and a trapper in Nobles County found 2 moths on April 1st. The Swift County trap is significant. I might have suspected an April fool's prank on the part of the trap cooperators but the weather systems at that time certainly could have transported moths into these areas.

BCW 2016-02 Map B

Cutworm eggs hatch at 90 degree-days (base 50F) and cutting begins at more than 300 degree-days after the moth flight(s). The freezing temperatures the night of April 3-4 may have harmed last week immigrant moth population.

Black cutworm moths are attracted to un-worked fields, particularly with winter annual or early germinating spring weeds. Most 2016 corn ground has not been worked this spring, and I am starting to see giant ragweed, common lambsquarters and kochia emerging. A new wild card could be the fields planted to cover crops that survived t he winter. These could be attractive sites for black cutworm egg-laying. For example, in 2014, some fields where corn was planted into winter rye cover crops saw black cutworm problems. Finally, some of the above-ground Bt traits provide control of black cutworm. Growers that have planted hybrids without Bt should pay particular attention to black cutworms when scouting this spring.

Will we have a problem this spring? 

It all depends on how many cutworms arrive in Minnesota, when and where they arrive.

- Bruce and Travis