VIEW ARTICLE

Postharvest Pathology and Mycotoxins

Factors Influencing the Susceptibility of Lemons to Infection by Geotrichum candidum. A. B. A. M. Baudoin, Former graduate research assistant, Department of Plant Pathology, University of California, Riverside 92521, Present address of senior author: Department of Plant Pathology and Physiology, Virginia Polytechnic Institute and State University, Blacksburg 24061; J. W. Eckert, professor of plant pathology, Department of Plant Pathology, University of California, Riverside 92521. Phytopathology 72:1592-1597. Accepted for publication 19 May 1982. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-1592.

Lemons differed in susceptibility to infection by Geotrichum candidum, the causal agent of sour rot. Inoculation of wounds in the peel resulted either in a rapidly developing soft rot within 5–6 days or in a dry arrested lesion. Differences in susceptibility of fruit lots were expressed in the percentage active lesions after 5 days or in the number of spores required for 50% active lesions (ED₅₀). The expansion rate of active lesions was not correlated with fruit susceptibility to infection. Differences in susceptibility between the lemon cultivars Lisbon and Eureka were not significant. Susceptibility increased with physiological age, ie, with color change from light green to yellow and with duration of storage. Treatment with ethylene accelerated this increase. Water uptake or water loss resulting in a change of 2–10% in fruit weight and a change of 0.6–3.0 bars in peel water potential reduced or increased, respectively, the ED₅₀ 3–30 times. The ED₅₀ for lemons picked at 1400 hours was 2–10 times higher than that for fruit picked at 0800 hours. Lemons picked after rainfall were more susceptible than those picked during a dry, sunny period.