April 9, 2007

 

How Has the Recent Cold Weather Affected Alfalfa & Alfalfa Weevils?

by Jim Fawcett

Temperatures in the teens and low 20s will at least cause some tissue damage in established alfalfa fields, and could cause more serious damage to the buds and crowns. Tissue damage often causes the leaves to have a near white appearance. It will take a week or more to determine if the cold temperatures have caused any permanent damage to the alfalfa. If the re-growth is showing evidence of freeze damage, plants should be dug and crowns split to check for damage. Healthy taproots are creamy-white in color, with a firm texture. Freeze-injured taproots will begin to be ‘watery’, tan/brown in color and beginning to soften. See Steve Barnhart’s article on the agronomy website for more information: http://www.agronext.iastate.edu/showitem.php?id=39.

The good news is that the cold temperatures should have killed any early hatched alfalfa weevils. Eggs are more protected though, and probably survived. Most eggs have not yet hatched, so assuming they survived, the current cold weather will not likely have a large impact on the weevil population.

 

 

What about Black Cutworms?

 

There have been a few captures of Black Cutworm moths in Iowa.  How has the cold weather impacted any eggs that were laid?  Marlin Rice is doing an experiment to answer that question.  Results should be available in about 2 weeks.

 

 

FOR YOUR CALENDAR

Wednesday, June 20 – Thursday, June 21 (9:00 a.m. – 4:00 p.m. each day), Hay Expo 2007 - Westgate, IA.  See http://www.hayexpo.com/ for details.

 

Thursday, June 21, 1:00 p.m., SE Iowa Research & Demonstration Farm Field Day – Crawfordsville.  Watch http://www.extension.iastate.edu/Pages/eccrops/meetserc.html as details emerge.