2019 UMN Cooperative Black Cutworm Trapping Network Report #1

Report #1 Week of March 30- April 5, 2019

For more information: Black Cutworm Reporting Network

April 12, 2019

Greetings:

The 2019 black cutworm (BCW) trapping season has started.

The risk of crop loss due to BCW cut plants varies greatly from year to year. An increase in the acres of non-Bt corn, adverse fall weather preventing tillage in some areas, and this spring’s wet field conditions delaying fieldwork, combine to increase the risk from BCW injury. The missing pieces of the 2019 BCW puzzle is when, where, and how many moths will arrive from the south. That is where the trapping network comes in.

black cutworm pheromone trapFigure 1. A black cutworm pheromone trap waiting for warmer weather and moths.

Female BCW moths release a unique chemical compound (pheromone) to attract males. The BCW pheromone trap includes a small lure impregnated with a synthetic version of this pheromone. Unfortunate male moths, mistaking the odors wafting from the trap for an unmated female, fly into the trap where the trap’s sticky bottom captures them. Doesn’t seem very sporting, does it? Anyhow, only BCW moths react to the pheromone and then, only for the few days after migrants arrive and complete mating.

This species-specificity and narrow capture window allows us to use these trap captures to locate when and where large flights of BCW migrate into Minnesota. This information helps us predict areas of Minnesota where corn, sugarbeets and other crops are at higher risk from damage, when crop injury will begin and just as importantly when cutting will stop.

MN counties with black cutworm trapsFigure 2. Counties with cooperators and black cutworm traps in 2019.

Counties that have one or more BCW pheromone traps are shown in Figure 2. Spring weather is variable and, as a result, local areas will have higher or lower populations. Based in part on where low-level jet streams with sustained southerly flows are most likely to arrive, trapping is concentrated in the southern part of MN.

We have a very good network of volunteer trappers this year checking traps daily and reporting their observations once a week. Thanks to the efforts of these volunteers, we should be able to do a respectable job of predicting BCW risk but, as France found with the Maginot line, problems can avoid a defensive system. In other words, field scouting is still important.

During the spring, results of the 2019 trap network captures and predictions of BCW cutting will be posted weekly at: Black Cutworm Reporting Network. More information on black cutworm biology and damage are locate at this site as well. There will be additional alerts for any BCW high-risk areas picked up by the network.

This project is supported, in part, by the farm families of Minnesota and their corn check-off investment.

Until next week,

Bruce Potter and Travis Vollmer