Comparative Studies with Two Geotrichum Species Inciting Postharvest Decays of Tomato Fruit. H. E. Moline, Research Plant Pathologist, U.S. Department of Agriculture, ARS, HSI, HQCL, Beltsville Agricultural Research Center, Beltsville, MD 20705. Plant Dis. 68:46-48. Accepted for publication 22 July 1983. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1984. DOI: 10.1094/PD-68-46.

Growth rates of Geotrichum candidum and G. penicillatum (ATCC 48024) were compared on mature green and red tomato fruit at 5, 10, 15, and 20 C and on potato-dextrose agar (PDA) at 5, 10, 15, 20, 25, 30, 35, and 40 C. The rate of infection of mature green fruit by G. penicillatum was less than that by G. candidum at all temperatures. Both fungi grew at the same rate on red fruit. G. penicillatum was less aggressive and had a slower growth rate than G. candidum on PDA at temperatures from 10 to 30 C. Fungicidal effects of several chemicals were studied on mature green and red fruit inoculated with spore suspensions of the two species. Sodium hypochlorite, benomyl, thiophanate methyl, and vinclozolin retarded growth of G. penicillatum on green fruit; imazalil and ferbam retarded lesion development on red fruit. Sodium bicarbonate and potassium sorbate retarded G. candidum growth on green fruit, and thiophanate methyl and sodium bicarbonate retarded fungal growth on red fruit. None of these fungicides, however, prevented decay caused by either fungus. This is the first reported incidence of G. penicillatum causing postharvest decay of tomatoes.

Keyword(s): sour rot, storage, watery rot.