Other fungi such as several Fusarium fungi, do not attack alfalfa except as crown invaders. Crown rots cause loss of stand and forage yield in several ways. If crowns are rotted severely enough, plants can die simply by being choked off. Carbohydrates for winter survival are stored in the crown and upper taproot. By rotting this area, crown rots also make alfalfa plants more sensitive to winter kill.
Some crown rot fungi produce toxins, thus weakening or even killing the plant.
Alfalfa breeders have not made an effort to breed for resistance to crown rots, primarily because literally dozens of fungi can cause these diseases. However, selecting a variety well-suited for local conditions will help in minimizing the impact of these diseases. Minimize crown injury. Injury to crowns creates wounds that allow infection by crown rot fungi living in the soil. Minimize traffic and grazing in alfalfa stands when the soil is wet, to minimize crown injury, Rotate alfalfa land to crops other than forage legumes.