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Soil-Borne Diseases of Onion

Howard Schwartz (May, 2011)

Summary

Colorado is a major producer of onions. Approximately 14,000 acres are planted annually on the Western Slope, in the Arkansas Valley and throughout northeastern Colorado. Yields often average 350 to 400 hundredweight per acre unless constraints, such as soil-borne diseases, become widespread and serious enough to limit production. Plant survival, bulb size and quality can be reduced and thereby affect crop productivity (up to 60 percent yield loss recorded) and profitability. Soil-borne disease problems of seeded and transplanted onions include: damping-off, pink root, fusarium basal or plate rot, bloat or stem and bulb nematode, and smut. This fact sheet describes the pathogens, their symptoms and methods of control.