Making thorough assessments of stand health can help Midwestern alfalfa growers determine whether or not to take fall cuttings, according to Rory Lewandowski and Marc Sulc, Extension educator and forage specialist, respectively, at Ohio State University (OSU).
In a recent edition of OSU’s C.O.R.N. (Crop Observation and Recommendation Network) Newsletter, the experts pointed to the following as factors to consider:
- Disease resistance: Cornell University research indicates that alfalfa varieties with improved disease resistance will be more tolerant to negative effects of a fall cutting because there is less total stress on the plant. Any of the newer varieties of alfalfa have good resistance to the major alfalfa diseases, Lewandowski and Sulc wrote.
- Soil fertility: High soil potassium can increase plant health and tolerance to fall cutting effects. A high soil pH of 6.8-7.0 will also reduce risks associated with fall cutting.
- Age of stand: Compared to older stands, stands under three years of age are more tolerant of fall cuttings.
- Protection from insects: Potato leafhopper control throughout the year will reduce plant stress and lead to strong, vigorous plants able to withstand fall cutting stress.
- Number of harvests during the season: Alfalfa cut three or more times before a fall cutting is at a higher risk for plant injury than alfalfa cut fewer times.
- Soil drainage: Alfalfa stands on well-drained soils tolerate late-fall cutting better than alfalfa on moderately or poorly drained soils.
Lewandowski and Sulc’s bottom line: In most years, Ohio growers can probably get away with cutting during fall without severe injury to stands. “But it is very probable that fall harvest robs yield next year, and it always increases risk of winter damage if the cutting date is such that alfalfa regrows without sufficient time to recharge what it used for that fall regrowth."
Taking all risk factors into consideration, the worst time to fall harvest in Ohio is most likely between Sept. 25 and Oct. 15, they agree. “If you do decide to cut during the fall critical period, leave several strips of alfalfa uncut in different parts of the field so you can compare the vigor of cut and uncut plants next year.”
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