Kansas State University


Extension Entomology

Alfalfa Update

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Once again we are in the midst of a typical Kansas spring with warm, bordering on hot, windy conditions interspersed with cold, windy conditions.  However, rainfall (or moisture in any form) has been pretty much lacking throughout south central and north central KS.  Again, as in most KS springs, the weather has variable effects on alfalfa and therefore, the alfalfa weevil.  Some fields are still showing effects of recent freezing temperatures.  Most of the yellowing/silver coloring in these fields is due to the weather.

Alfalfa freeze close

alfalfa freeze field

Fields that were sprayed before last week’s freeze still have live larvae but they are yellowish and moribund compared to larvae from fields not yet treated.

moribund larva

healthy larvae

However, fields not yet treated should be closely monitored as weevil feeding has been significantly slowed by the cold weather and has just started to become noticeable.

silvering alfalfa

This feeding will only intensify for about the next 7-10 days at temperatures ranging between 45-75°F.

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