THE CRITICAL FALL HARVEST PERIOD FOR ALFALFA IN INTERIOR BRITISH COLUMBIA
Alfalfa (Medicago sativa L.) was grown under irrigation and harvested three times each year at Kamloops, British Columbia. The third cut was taken at five or six different times between 15 Aug. and 1 Nov. to identify the critical fall harvest period. Harvesting the third cut on 15 Aug. or 20 Aug. caused the most decrease in the yield of the first cut in the next year; thus the critical fall harvest period is from about 15 Aug. to 15 Sept. On average the total annual yield varied by only about 10% for the different times of third cut. When the third cutting was made on 15 Sept. or later, the average total yield varied by only about 6%. The winters of 3 of the 6 yr of the experiment were colder than normal. Thus, when yield is of prime concern, it is recommended that the timing of the third cut in interior B.C. be taken between 15 Sept. and 16 Oct.Key words: Alfalfa, cutting management, winter injury, yield, fall harvest period, Medicago sativa