FUSARIUM ROOT-ROT OF SWEET-POTATOES

F. solani was responsible for a newly recognized root rot of stored sweet potatoes. The disease is characterized by circular, necrotic lesions with superficial, concentric rings radiating from wound infection sites. The infection progresses internally beyond the vascular ring and may rot the entire root. Roots of cv. Jewel were more susceptible than were roots of ''Jersey Orange'', ''Georgia Red'', ''Centennial'', ''Nugget'' or ''Porto Rico''. Infection of succulent vine cuttings of ''Jewel'' and ''Porto Rico'' was limited to a necrosis of internodal tissue below the 1st node with no detectable effect on plant growth. Fruits of apple, cucumber, eggplant, pepper, squash and tomato and potato tubers were susceptible. The optimum temperature for F. solani isolates in culture was 28.degree. C; optimal temperature for disease development in enlarged roots was 24.degree. C. Control of the disease on ''Jewel'' roots was achieved by either curing immediately following harvest or treatment with thiabendazole.