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2024 Weevil Watch

BY Dairyland Seed Agronomy Team

Perhaps not surprising given the warm spring, alfalfa weevil pressure has been showing up about a week earlier than the 2023 season. Southern portions of Minnesota, Wisconsin and Michigan are experiencing weevil pressure and many producers have been treating fields accordingly. If you don’t have a handle on pressure in your area, now is the time to scout.

  • Timing: Watch for feeding from ~300 GDUs, through second crop. Rarely do issues show up in third or fourth crop.
  • Identification: The pale-green larvae have black heads and tend to feed on the young growth at the top of the plants. Adults, found after 800 GDUs, are gray beetles with small snouts.
  • Response: Sweep nets are good for pest survey, but feeding observations are key. If 40% of plants show signs of feeding and harvest is more than 10 days out, consider spraying an insecticide to manage the weevils. When spraying an insecticide be mindful of that products pre harvest interval days (PHI) utilizing a product with a PHI of 10 or less. If the normal cutting schedule puts harvest at less than 10 days, go cut immediately. Early harvest will save an insecticide application.
  • Follow-up: Watch 2nd crop regrowth carefully for continued feeding. If weevils are present and regrowth does not start 3-4 days after cutting, spray with an insecticide immediately.

 

 

Brian Weller
Brian Weller
Western Region
507.456.3034
Rod Moran
Rod Moran
Western Region
507.456.3034
Dan Ritter
Dan Ritter
Central Region
219.863.0583
Branden Furseth
Branden Furseth
Northern Region
608.513.4265
Mark Gibson
Mark Gibson
Eastern Region
260.330.8968
Amanda Goffnett
Amanda Goffnett
Eastern Region
989.400.3793
Ryan Mueller
Ryan Mueller
Eastern Region
989.400.3793
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