Predisposition of Citrus Fruits to Sour Rot When Submerged in Water. Eliahou Cohen, Associate Research Professor, Department of Fruit and Vegetable Storage, A.R.O., The Volcani Center, Bet Dagan, 50250, Israel. C. W. Coggins, Jr., and J. W. Eckert. Professor, Department of Botany and Plant Sciences, and Professor, Department of Plant Pathology, University of California, Riverside 92521. Plant Dis. 75:166-168. Accepted for publication 30 July 1990. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-0166.

Sour rot developed at more than 90% of the wounded sites on lemons, oranges, and grapefruit inoculated with 5 ?l of an aqueous suspension of Geotrichum candidum conidia (10⁴–10⁶/ml) when inoculated fruit were submerged in water at room temperature for 24–36 hr before storage. The frequency of infection was similar in yellow fruit exposed to a water-saturated atmosphere, but this treatment was much less effective than prolonged submersion in water for stimulating sour rot in silver lemons and in mature and immature green fruit. The maximum effect of the water treatment was induced by inoculation with a minimum of 10⁵ conidia per milliliter, followed by immersion in water at room temperature for at least 24 hr. This simple procedure for predisposition of citrus fruits to sour rot can be scaled up for fungicide tests and research projects that require a dependable, high level of infection.