CEW Alert Continues for Southern Minnesota

Bill Hutchison, MN Extension IPM Program, UMN

August 10, 2016

As with last week's catch at Rosemount and Blue Earth, Corn Earworm moth catch continues to increase at these locations. At Blue Earth, trap catch went up to 185 on 8/4 and 198 on 8/5. CEW Moth flight to date, has been updated, for all those reporting, as of today: http://www.vegedge.umn.edu/moth-data/cew-info

A challenge for processors and fresh-market growers

Also, noted in the Blue Earth graph, the flight this year is much higher than the past two years (essentially back to a more "normal" flight); this increase is not surprising given the recent Low pressure system that moved through the state. In brief, the Lows typically bring warm/humid air from southern states northward. As these fronts converge with a High pressure front, this typically results in a rainfall event, and facilitates both the movement (migration) of insects northward, and their deposition wherever these fronts converge; thus can be spotty depending on how the fronts converge, and over which states, etc.  See note below for the CEW forecast.  With a new Low system moving in today to Friday, the risk of ongoing CEW moth flights in MN continues.

CEW will therefore be a challenge for fresh-market growers who have not planted Bt sweet corn, and it will be wise to be vigilant in scouting and tracking the on-going trap catch in southern to central MN carefully. Again, having a CEW pheromone trap at each farm/production area is best to maintain the best indication of CEW pressure on specific farms.  In addition, the CEW flight should be followed carefully for all corn now silking and late-planted sweet corn, into September. 

For growers in western Wisconsin, CEW trap catch can be monitored via the WI Dept. of Agric. pest report: (updated on Thursdays), which can be viewed here

CEW Migration

For CEW, as one of our annual pests that does not overwinter in the upper midwest, and thus relies on southerly Low Level Jet airflows into the state, you may be interested in tracking the CEW Forecast system developed by a colleague interested in insect migration: meteorologist, Mike Sandstrom. View the page InsectForecast here

CEW moths

CEW moths caught in a Hartstack Trap.