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Postharvest Temperature Effects on Wound Healing and Surface Rot in Sweetpotato. L. W. Nielsen, Professor, Department of Plant Pathology, North Carolina State University, Raleigh 27607; J. T. Johnson, Research Technician, Department of Plant Pathology, North Carolina State University, Raleigh 27607. Phytopathology 64:967-970. Accepted for publication 5 February 1974. DOI: 10.1094/Phyto-64-967.

Freshly harvested roots of sweet potato cultivars ‘Porto Rico’, ‘Centennial’, ‘Nugget’, and ‘Goldrush’ were immersed for 2 h in water baths at five temp from 4.5 to 45 C, or exposed to cold air at 3 C, or to sunlight to obtain differential root temp. The temp-treated roots were artifically wounded, cured at 29 C for 7 days, stored at 13 C for 6 mo. and examined for wound infection by Fusarium oxysporum. In general, surface rot developed in more wounds of roots exposed to 4.5 and 45 C, and least developed in wounds of roots exposed to 32 or 38 C. The cultivars responded similarly, but differed in magnitude of response. More wound infections developed in roots of cultivars Centennial and Goldrush than in those of Nugget and Porto Rico. The relative infection was related to the rapidity of wound healing and retardation of the healing processes by the 4.5 and 45 C treatments. Suberin had formed across root wounds of Porto Rico and Nugget exposed to 38 C in 6 days, but it was incomplete across root wounds in Centennial and Goldrush. Temperatures of 4.5 and 45 C retarded wound healing in roots of all cultivars, and the phellogen formed at greater distances below the wound surface. Suberization was retarded more and phellogen formed deeper in the tissues in Goldrush and Centennial roots than in Porto Rico and Nugget roots.

Additional keywords: Fusarium oxysporum, Ipomoea batatas.