Alfalfa Weevil Update - 04/04/25

Last week’s numbers – and the size of the weevils found during sampling suggested the year’s alfalfa weevil hatch had (for the most part…more in a companion article) just begun. Infestation levels ranged from 0-15% (5.5% average) with very little feeding injury. This week has been a different story:

The light blue ‘zone’ indicates the treatment threshold often used by K-State Extension Field Crops Entomologist Dr. Jeff Whitworth. Once weevils/stem reach the 35-50% level, treatment should be considered – and in 4/6 sites we’ve done so in the last week. If you haven’t been sampling, it’s time to.

Treatment?

If consideration of treatment options is next on your to-do list, the most recent KSU weevil treatment trials are all posted at the bottom of our Meadowlark Extension District Crops & Soils page. Any product will do a fairly good job, but some products tend to work a little better than others.

NOTE: always be sure to read and follow label directions to make sure products are still appropriately labeled. The label IS the law!

Carrier rates matter as well as this 2023 trial from Dr. Whitworth illustrates. While lower gallonage carrier rates were effective – higher rates performed slightly better.

If you have any questions or want to share what you are seeing for weevil pressure, drop me a line!