2017 U of MN Cooperative Black Cutworm Trapping Network Issue 5

Report #5 Week of April 22-28, 2017

This report is also available in a print-friendly pdf format: 2017 Black Cutworm Network Issue 5

Black cutworm captures in southern Minnesota for the week of April 22-28, 2017.Low levels of moth activity for the week. Again, locations scattered through the trapping area reported captures (Figure 1).

A few traps were as high as 3 moths/2 nights. Looks like there were two small immigration events. Other locations with captures are listed below:

  • Brown - 3 on the 26th
  • Brown - 2 on the 26th
  • Dakota - 2 on the 25th
  • Faribault - 1 on the 25th
  • Lac Qui Parle - 1 on the 24th
  • McLeod - 1 on the 24th
  • Nicollet - 1 on the 26th
  • Nicollet - 1 on the 23rd, 1 on the 26th
  • Nobles - 1 on the 23rd, 1 on the 24th and 1 on the 25th
  • Redwood - 1 on the 24th
  • Rock - 1 on the 26th
  • Sibley - 1 on the 23rd
  • Steele - 1 on the 23rd
  • Swift - 1 on the 22nd, 2 on the 23rd
  • Waseca - 1 on the 23rd

You can compare these dates with rainfall maps to see where these systems tracked.

The only significant flight detected has been the localized April 15 flight in Brown and Redwood counties. Larvae from this flight could be large enough to cut small corn or sugarbeets in about 2 weeks, depending on weather. As of now, it still looks the highest probability for any threatening black cutworm populations is in the western Brown, eastern Redwood Co. area.

Cumulative Degree-Days

(Base 50oF)

Black Cutworm

Stage

Black Cutworm

Activity

0 (Biofix) significant moth capture egg-laying
90 egg hatch
91-311 1st-3rd instar leaf feeding
312-364 4th instar cutting begins
365-430 5th instar cutting
431-640 6th-7th instar cutting slows
641-989 pupa no feeding

Within this area, you may want to plan on scouting later-tilled or minimum-tilled fields and fields with heavy spring weed populations or overwintering cover crops a bit harder.

As of today, using a combination of current and historical data, there are less than 60 cumulative degree-days (base 50°F) and any eggs should not yet have hatched. Larvae from the April 15 flight are projected to be large enough to cut for after May 21. Fortunately, black cutworm and corn have approximately the same base development temperature. The U2U corn growing degree-day calculator http://mrcc.sws.uiuc.edu/U2U/ at the Midwest Regional Climate Center is very helpful in projecting cutworm (and corn) development.

There is still time for some significant migration to occur. Some moths may have snuck in with the Monday snow!

Until next week, 

Bruce Potter and Travis Vollmer