By Ayman Mostafa and Mike Ottman
Stand Replacement: The decision to replace alfalfa stands is based on stand establishment costs, opportunities in other crops, hay price, and yield of the alfalfa stand in question. Historical yields for the farm can provide a good idea whether or not a stand should be replaced. A stand should be replaced if plant density is less than 4 to 6 plants per square foot or if the number of stems is less than 40 per square foot. Stands may need replacement regardless of average plant or stem density if plants are not uniformly distributed or if many bare spots exist where the sun at noon hits the soil surface. Renovating alfalfa stands by overseeding with alfalfa is usually not effective except in bare spots greater than a 12-18 inch diameter. To avoid autotoxicity, delay seeding alfalfa into a field previously in alfalfa by at least 2 weeks after tillage or 3 weeks after herbicide-kill of the old stand.
Weed Control: Now is the time to apply pre-emergence herbicides for winter annual weed control in established stands. It’s better to be a month early than a day late with pre-emergent applications.