Drought, potato leafhoppers and frequent cutting schedules were prevalent in Ohio this summer, and all can contribute to shorter alfalfa stand lives. So taking the last cutting by recommended cutoff dates will be especially important in 2012, say Rory Lewandowski and Mark Sulc, Ohio State University Extension educator and forage specialist, respectively.
According to Ohio State’s Ohio Agronomy Guide, the risk to alfalfa stands is minimized when the last harvest is completed by Sept. 7 in northern Ohio, Sept. 12 in central Ohio and Sept. 15 in the southern part of the state. Cutting later than that can limit the accumulation of carbohydrate and protein reserves that plants need for winter survival and to start early growth in spring, warn Lewandowski and Sulc.
After the last cutting, they suggest that growers do stand evaluations to assess how their stands came through this difficult year and what might be expected next spring. They should look at stand density as measured by plants per square foot. The guidelines are: seeding year, 25-30; second year, 10-15; third year and older, five to six plants per square foot.
Next, dig and count the alfalfa plants in a 1- to 2-sq-ft area at several random field locations. Split open the roots lengthwise to observe tissue health. In healthy stands, fewer than 30% of plants will show significant discoloration and rot in the crown and taproot, and vigorous crown shoots are symmetrically distributed around the crown. If greater than 50% of the plants show symptoms of crown or root rot, plan to interseed another legume or an improved grass species, or rotate to another crop, say the Extension specialists.