It may be tempting to squeeze out one last cutting of alfalfa in mid-October, especially if a late rain encourages late growth, but producers must consider the long-term effects of such a decision, says Jim Shroyer, K-State Research and Extension crop production specialist.
"The last cutting of alfalfa for the year should be timed carefully since it could have a long-lasting impact on the productivity of the stand," Shroyer says.
At this stage of the growing season, plants need to store enough carbohydrates to survive the winter, the agronomist explains. "To do that, the last cutting has to be timed properly. If root reserves are not replenished adequately before the first killing freeze (24 to 26 degrees F.) in the fall, the stand is more susceptible to winter damage than it would be normally. That could result in slower early growth next spring."
The last cutting, prior to fall dormancy, should be made so there are 8 to 12 inches of foliage, or four to six weeks of growth time, before the average killing freeze date, Shroyer says. This should allow adequate time for replenishment of root reserves.
For northern areas of the state, particularly northwest, late September should be the target date for the last cutting before dormancy, he advises. The first week of October is the cutoff for southeast Kansas.
Later cutting dates could reduce root reserves during a critical time. "About the worst thing that could happen to an alfalfa stand that is cut in mid-October would be for the plants to regrow about 3 to 6 inches and then get a killing frost. In that scenario, the root carbohydrate reserves would be at a low point going into winter," Shroyer says.
After a killing freeze, the remaining forage (if any) can be hayed safely, he added. However, the producer should act quickly because the leaves will soon drop off.
More information on alfalfa management is available at county and district K-State Research and Extension offices or on the Web in the K-State publication C-683 "Alfalfa Production Handbook," at: www.oznet.ksu.edu/library/crpsl2/c683.pdf.