Allow adequate growth before freezedown. Alfalfa needs four to six weeks of regrowth between the final harvest and freezedown. This is necessary in order to have sufficient root reserves to withstand winter weather and to resist crown rot infections during the dormant season. Following freezedown, the forage can be harvested or grazed as desired. Weeds Several insects create wounds that allow crown rot fungi and wilt pathogens to invade alfalfa plants .
Weeds can also aggravate some diseases, if growth is dense and rank.
Dense weed growth reduces air circulation and slows drying of foliage, making conditions more favorable for diseases of leaves and stems. Minimize Crown Injury Injuries to the crown provide infection sites for crown rot fungi. Avoid practices that injure crowns such as grazing or using heavy equipment when the soil is wet.