2017 U of MN Cooperative Black Cutworm Trapping Network Issue 8

Black cutworm moth captures May 13-19, 2017

Figure 1. Black cutworm moth captures May 13-19.

Report #8 Week of May 13 - May 19, 2017

This report is also available in a print-friendly pdf format: 2017 Black Cutworm Network Issue 8

Last Friday was the last trapping date for 2017.

There were no significant captures (8 or more moths over a 2-night period) for any of the traps that were still being checked the past week. The trend for captures but low numbers continued. (Figure 1, Table1)

Most, but unfortunately not all, soybean residue has been worked at least once this spring and the row crops at most risk (usually corn and sugarbeets) have been planted.

There is a tendency for black cutworms to lay eggs in soybean residue over corn. However, this spring, in some wetter areas of MN, there are fields of unworked corn residue with heavy lambsquarters, giant ragweed or late- killed cover crops. These fields could be attractive to late-arriving moths. The possibility of cutworm should not be ignored when scouting soybean or other crops planted into these fields.

Table 1. Location & number of black cutworm moths captured May 13-19, 2017
County Moth Captures Maximum 2-Night Total
Dakota 4 - 18th to 19th 2
Jackson 2 - 15th
Kandiyohi 2 - 14th
Lac Qui Parle 3 - 16th
McLeod 1 - 15th
Redwood 2 - 15th
Renville 1 - 18th
Rock 1 - 16th1 - 17th2 - 18th1 - 19th 3
Steele 1 - 13th1 - 16th2 - 17th 3
Stevens 1 - 16th
Swift 1 - 16h
Swift 1 - 13th1 - 15th2 - 16th 2
Waseca 1 - 17th
Waseca 1 - 16th
2017 trapping season black cutworm moth captures

Figure 2. Counties where significant moth captures occurred during 2017 are shaded in red. Numbers relate to total moths captured at that sight.

This year, trap captures in Minnesota were low overall - some traps did not capture any black cutworm moths this spring with only three traps reporting significant captures (Figure 2). This does not mean that there was anything wrong with the trap, trap location or trapper. Rather, it shows just how spotty and sporadic these immigration events are.

Fortunately, black cutworm outbreaks are relatively rare and so far that looks like it will be the case in 2017. As of now, it still looks the highest probability for any threatening black cutworm populations is in the western Brown, eastern Redwood Co. Rock Co. and nearby areas. The Rock county trap captures are why we cannot just rely on the location of storms to detect flights. Also, other areas cannot be assumed risk-free because of the very localized nature of some of these immigrations. Don’t ignore black and other cutworm species when scouting.

Below are dates and locations of significant flights and estimates of cutworm stages and for these flights, when cutting is projected to start with 4th instar larvae (300 DD) and cutting projected to end as the larvae pupate (640 DD). Cooler, cool weather continued to slow cutworm (and crop) development.

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. It’s an interesting site.

2017 Black cutworm cutting projections 5/24/2017
Biofix flight date Counties Accumulated degree-days Estimated stage Projected cutting start Projected pupation
April 15 Brown 272 3rd instar May 31 June 23
April 29 Redwood 220 2nd instar June 6 June 25
May 7 Rock 178 2nd instar June 10 June 27

Fields worked and planted before these flight dates are at less attractive for egg laying and risk for damage.

Black cutworm moths often deposit their eggs in low lying areas of the field. In parts of MN some of these have experienced saturated and flooded soils. Where any crop needs replanting because of standing water, the small bright spot is that any cutworms present have likely drowned.

Degree-day models, tips to prioritize scouting and other black cutworm facts can be found at the black cutworm reporting network at the top of this article.

Thanks to all of those who ran traps and reported data this year. Your assistance was much appreciated.  Also thanks to the Minnesota Corn Research and Promotion Council for supporting this project. 

2017 Black Cutworm Trap Cooperators
Ron Anderson Larry Arentson Kevin Ballman
Lesa Behnken Mark Bents Mark Bernard
Bob Braun Steve Commerford Kerry Dittbenner
Aaron Erickson Jason Ertl Carmen Fernholz
Dorian Gatchell Jodie Getting Mark Glady
Justin Golden Cody Groen Dan Haubrich
Pat and Kyle Hennen Bryon & Kristy Kittleson Tom Klader
Brian Kohler Justin Krell AJ & Rochelle Krusemark
Dan Martens Bill Miller Tim Moline
David Nicolai Evan Oberdieck Tim Olson
Nick Pieske Gary Prescher Matt Prigge
Curt Reese Melinda Robertson Tom Sandager
Dave Schwartz Rod Sommerfield Gale Symens
Damon Traxler Travis Vollmer Brian Weller
Logan Wenzel Nathan Wilber Nathan Winter/Karen Johnson
Richard Wurtzberger Jon Zuk

Please let us know of any cutworm infestations you encounter this spring.

Bruce Potter and Travis Vollmer