Symptoms
Infection commonly occurs when Fusarium moniliforme enters the roots and spreads throughout the plant. Symptoms of asparagus crown rot include wilting of mature plants during hot summer weather, stunting, yellowing, seedling blight, and death. Infected areas of the crown turn brownish in color as cells that transport water and nutrients become clogged due to the infection. Cutting open affected plants reveals dark, reddish-brown colored decay of lower stems, crowns, and roots. Later, portions of the crown begin to dry up until the entire plant dies. This leads to large gaps in the asparagus field and significantly lowers crop production. Fusarium-infected plants increase in number until the crop is too sparse to harvest economically.

Signs
The positive diagnosis of Fusarium moniliforme is based on laboratory detection of the fungus associated with typical symptoms on the plant.

Life Cycle
Fusarium moniliforme survives in crown and stem lesions of diseased, old asparagus plantings. Fungal spores are spread by air currents and on the surface of contaminated asparagus seeds.

Management
Fusarium disease is extremely difficult to manage once the fungus is established in an asparagus field. Primary controls are choosing healthy, fusarium-tolerant varieties of plants obtained from a reputable source, and planting in fields not previously used for asparagus. Fusarium-resistant varieties for Minnesota growers include Jersey Giant and Viking KB3. Controlling pests, diseases, weeds, and avoiding excessive harvesting limits fusarium disease.

References

• Gould, S. L. Disease-Resistant Vegetable Varieties. University of Minnesota Extension Service folder 02412, 1994.
• Sherf, A. F. and A. A. MacHab. Vegetable Diseases and Their Control, 2nd Ed. New York: John Wiley & Sons, 1986.

• Growing Asparagus in Minnesota

P257A
03/02