2017 U of MN Cooperative Black Cutworm Trapping Network Issue 7

Report #7 Week of May 6 - May 12, 2017

This report is also available in a print-friendly pdf format: 2017 Black Cutworm Network Issue 7

Once again, locations scattered throughout the trapping area reported small captures (Figure 1). Trap captures in Minnesota this year remain low overall.

There is some risk of damage from black cutworm in 2017. It appears to be relatively low and not widespread.

This week a Rock County trap was quite active and had two consecutive 2 night captures of 11 moths.

This adds another area in Minnesota with an elevated risk from black cutworm damage.

There were quite a few non-reporting counties this week and corn planting has wrapped up in much of southern Minnesota.

All other traps captured 0-4 cutworm moths. Other locations with captures are listed below:

County Moth Captures Maximum 2 Night Total
Brown 1 on the 11th
Dakota 2 on the 9th
Jackson 1 on the 8th
Lac Qui Parle 1 on the 8th
Meeker 1 on the 6th1 on the 12th
Olmsted 1 on the 10th
Rock 2 on the 6th, 7 on the 8th, 4 on the 9th, 1 on the 11th 11 (2 night total)
Sibley 1 on the 6th, 1 on the 7th 2 (2 night total)
Steele 2 on the 9th, 1 on the 10th, 1 on the 12th  3 (2 night total)
Swift 1 on the 7th, 1 on the 8th 2 (2 night total)
Swift 1 on the 10th, 2 on the 11th 3 (2 night total)
Wabasha 3 on the 9th
Waseca 1 on the 7th, 1 on the 8th 2 (2 night total)
Yellow Medicine 3 on the 10th

There have been two other significant flights April 15 and April 29. Both have been into the Brown and Redwood county area. How damaging and when cutting occurs depends on soil temperatures and how quickly corn develops. Where fields were worked before these dates risk of black cutworm damage is lowered.

As of now, it still looks the highest probability for any threatening black cutworm populations is in the western Brown, eastern Redwood Co. area. Later, I would also pay attention to Rock Co. and nearby areas along the Iowa border that experienced the same rain patterns as Rock County May 6-7. 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 and cutting projected to end as the larvae pupate. Cooler, recent weather slowed cutworm development…and crops.

2017 Black Cutworm Cutting Projections 5/18/17
Biofix Flight Date Counties Accumulated Degree-Days Estimated Stage Projected Cutting Start Projected Pupation
April 15 Brown 262 3rd instar May 29 June 16
April 29 Redwood 208 2nd instar June 3 June 23
May 7  Rock 165 2nd instar June 6 June 26

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.

Until next week,

Bruce Potter and Travis Vollmer