Fusarium dry rot is an important postharvest disease of potato worldwide. Fusarium dry rot can be caused by several different Fusarium spp, including F. solani, F. sambucinum, F. avenaceum, F. culmorum, and F. oxysporum, but F. solani appears to be the most aggressive and important. Dry rot Fusarium spp. originate from contaminated seed or infested soils, infecting tubers through wounds in the periderm that are common after potato cutting and handling practices. Fusarium spp. introduced into soils by contaminated seed can persist for years. Soilborne inoculum can infect tubers through wounds caused by other pathogens, insects, or during harvest and handling.
Fusarium dry rot symptoms appear as small brown areas that develop about 1 month after harvest. The affected area enlarges in all directions, causing sinking and wrinkling of the periderm over the lesion. Fungal mycelium and spores often line dry rot cavities, and may emerge from the dead periderm. Tubers may completely rot, shrivel, and become mummified after long periods of time in storage. The disease reduces yield, marketability, and seed quality. Direct yield losses range from 6 to 25%, but may be as high as 60% with severe infections.
No biological control practices have been developed for Fusarium dry rot.
Plant high quality seed free from Fusarium dry rot pathogens into soils without a history of Fusarium dry rot. Varieties vary in their reaction to dry rot, and highly susceptible varieties should be avoided. Harvest tubers at least 14 days after vine kill to promote good skin set and reduce skinning injury that can increase storage dry rot. Avoid harvesting cold tubers that are more susceptible to injury. Provide conditions that promote rapid wound healing early in storage, including high humidity, good aeration, and temperatures of 55 to 64ºF for 14 to 21 days. Since Fusarium dry rot increases with length in storage, short-term storage is advisable for fields where severe infection is expected.
Post-harvest fungicide applications can reduce Fusarium dry rot losses, but strains of F. solani and F. sambucinum resistant to benzimidazole fungicides are widespread.
Trade Name |
Target Pathogen |
Rate |
Remarks |
Chloroine |
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Agclor 310 |
Decay causing organisms |
10-15 fl oz per 100 gal water |
For treating potatoes in a pit system use a concentration of 100 to 15 ppm Cl2. |
Thiabendazole |
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Decco Salt No. 19 |
Fusarium Tuber rot |
5.67 per 2000 lb of potatoes |
Seed potatoes should be treated before cutting. |
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Mertect 340-F |
Fusarium Tuber rot |
Conveyer line: 0.42 fl oz per 2000 lb of potatoes; Dipping: 0.42 fl oz per 1 gal water, dip tubers for 20 sec. |
Seed potatoes should be treated before |
The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality. |
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Categories: Potato, Disease, Fusarium Dry Rot
Date: 03/29/05