Impact
Fusarium dry rot is caused by several common species of the soilborne fungus Fusarium. Fusarium dry rot causes losses in storage of both seed and commercial potatoes. It is a potential cause of seed piece decay after planting. Disease incidence varies from season to season in the San Luis Valley.

Fusarium dry rot.

Descriptions and Symptoms
	Small, brown lesions at wound sites occur three to four weeks after harvest and continue to enlarge during storage.
	Infected areas of tubers are sunken or wrinkled. Rotted tissues are brown or gray to black.
	Internal cavities often develop in rotted tissues and contain white, yellow or pink mycelium that are visible when tubers are cut.
	At low storage temperatures, internal tissues often become firm and dry or even powdery.
	Infection proceeds rapidly at temperatures above 50 degrees F, but ceases and is dormant if the temperature is lowered to 40 degrees F.
	Poor stands may result from seed piece decay, especially if the cut surfaces of the seed pieces are not properly suberized.
	A slimy rot often develops when secondary soft rot bacteria become established.
Integrated Management
	Manage harvest procedures and storage operations to minimize bruising and to promote raped healing of harvest wounds.
	Apply fungicides to tubers that will be sotred if Fusarium dry rot is anticipated.
	Manage bin filling to minimize soil and debris in the pile.
	Hold newly harvested potatoes at 50 to 60 degrees F and 95 to 99 percent relative humidity to promote rapid wound healing. Following the curing period, lower temperatures to a level appropreate for long-term storage.
	Treat cut seed tubers with a fungicide, if justified. Plant immediately under appropriate field conditions, or allow to suberize at 55 to 60 degrees F and 95 to 99 percent relative humidity for at least 72 hours.
	Avoid cutting seed tubers and the use of pick-type planters.

This material is based on work supported by the San Luis Valley Water Quality Demonstration Project Best Management Practices Advisory Committee, Colorado State University Cooperative Extension, Farm Service Agency, Natural Resources Conservation Service, and the U.S. Department of Agriculture under authorization as 1991 U.S. Department of Agriculture Water Quality Demonstration Project.