Did weeds take over your alfalfa this summer? Well, join the crowd. So, why were the weeds so vigorous and what might happen to your alfalfa?
Weeds seemed to show up everywhere in alfalfa fields during August. And I'm not exactly sure why. One thing is for sure, though. The weeds were worst in older fields, thinner stands, and in areas where rainfall was higher than normal.
Summer weeds that invade alfalfa when rain is heavy isn't unusual, especially if it is wet right after harvest. Alfalfa stubble just doesn't compete well with weeds, so weed growth gets a jump start on the alfalfa.
If the alfalfa plants are healthy and vigorous, though, this weed invasion should be just a temporary problem. After the next cutting, or maybe as late a next year, most weeds will disappear and the alfalfa will take over again.
What I'm more concerned about are your older fields, those fields starting to get a little thin. I've noticed this year that many alfalfa fields seemed to be getting weaker and weaker as the year went on, especially if they were harvested within a month of the previous cut. What I think is happening is that alfalfa plants in many fields have slowly been weakened naturally by root and crown diseases, but they weren't killed. Then, as the summer went on, the weakened root systems eventually couldn't handle the stress caused by frequent harvesting. So plants slowly died. And weeds invaded the open areas.
If this scenario describes one or more of your alfalfa fields, check it closely this fall. It might be time to reseed.
Preparing to reseed now will help avoid bad surprises next spring.
Written by: Bruce Anderson, Extension Professor, University of Nebraska-Lincoln, 402-472-6237