Pictured: True armyworm larva. Photo by K. Hamilton
True armyworm larvae are beginning to migrate into corn field edge rows and should be detectable in taller fields by scouting for plants with irregular, ragged edges and frass. As a reminder, it is normal to see a few edge row plants with armyworm feeding, according to the Department of Agriculture, Trade and Consumer Protection Pest Survey Program.
Counts must reach two or more armyworms (0.75 to 1.0 inch or smaller) per corn plant on 25 percent of the plants, or one worm per corn plant on 75 percent of the plants, to qualify for treatment. No significant infestations have been observed by DATCP as of June 4, but early to mid-June is a critical time to step up scouting outer corn rows and lodged areas of wheat fields for larvae.
DATCP’s True Armyworm Network has completed week 10 of monitoring and the cumulative count is 9,981 moths in 61 traps, or 164 moths per trap average. Last year at this time, the average was 148 armyworm moths per trap. The lull in moth activity reported by cooperators over the past three to four weeks signals that most armyworms are now in the feeding larval stages rather than the mating adult stage.
Activity in traps will pick up again by late June and the new round of moths, expected during weeks 12-14, will produce second-generation eggs. The late summer generation of armyworms will be even more critical to scout for to prevent July and early August infestations.
Learn more: https://datcp.wi.gov/Pages/Programs_Services/TrapNetworks.aspx
