Fields suffering from “windrow disease,” as Bruce Anderson calls it, are a trial for hay growers.

"Windrow disease is the name I give to the striped appearance in fields where alfalfa windrows remained so long that regrowth was delayed," explains the University of Nebraska Extension forage specialist. "Usually it’s due to rained-on hay, but also sometimes to insects.

“Weeds often invade, requiring spraying to maintain quality and protect stands,” he explains. “And during the next growth period, plants that were not smothered regrow rapidly, while plants underneath the windrow suffer delays.”

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"When you go to the work of putting up the best forage you can, you might as well put it in storage," says Gary Knutson, Volga, SD, grower.

As a result, parts of the field will begin to bloom, while windrow-stressed plants are still short and tender. Hay farmers are left to wonder when they should take the next crop.

They should consider two factors before deciding when to cut. One is whether their alfalfa is healthy and regrowing well. “If not, wait to cut until stunted plants begin to bloom so you can avoid weakening them even more.” Secondly, if the alfalfa is in good shape, producers should cut when the crop will best meet the needs of their animals, he says.

“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 cattle don’t need quality hay, so stunted plants can be allowed to recover and cut pre-bloom, Anderson says. “Hopefully, by next cut, growth will be more uniform, plants will be healthy, and production will be back to normal.”