Posted 29 June 2015. PMN Crop News.
Managing Windrow Disease in Alfalfa
Source: University of Nebraska Press Release. plantpathology.unl.edu
Lincoln, Nebraska (June 19, 2015)--Rained-on hay is always difficult to manage, but this year maybe more than usual. The "windrow disease" that often follows presents lingering problems.
Windrow disease — that's the name I give to the striped appearance in fields where alfalfa windrows remained so long that regrowth was delayed — is usually due to rained-on hay and sometimes, insects.
Windrow disease presents special challenges. Weeds often invade, requiring spraying to maintain quality and protect stands. During the next growth period, plants that were not smothered regrow rapidly, while plants underneath the windrow suffer delays. Part of the field often will begin to bloom while windrow-stressed plants are still short and tender.
This brings harvest timing into question: Should you cut when the first plants begin to bloom or wait until injured plants are ready?
Two factors can help guide your decision — the health and vigor of your stand and the nutrient needs of your livestock. For example, is your alfalfa healthy and regrowing well? If not, wait to cut until stunted plants begin to bloom so you can avoid weakening them even more. But, if your alfalfa is in good shape, cut when it will best meet the needs of your animals. Dairy cows need alfalfa that is cut early, so harvest when the first plants begin to bloom. Regrowth of injured plants may be slow after cutting, but this sacrifice is needed for profitable milk production. Beef cows, though, do not need such rich hay. In this case let stunted plants recover, and then cut when they are ready to bloom.
By next cut, it's hoped growth will be more uniform, plants healthy, and production back to normal.