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Postharvest Pathology and Mycotoxins

A Fungicide-Wax Treatment to Suppress Botrytis cinerea and Protect Fresh-Market Tomatoes. G. A. Chastagner, Postgraduate research associate, Department of Plant Pathology, University of California, Davis, CA 95616, Present address of senior author: Western Washington Research and Extension Center, Washington State University, Puyallup, WA 98371; J. M. Ogawa, professor, Department of Plant Pathology, University of California, Davis, CA 95616. Phytopathology 69:59-63. Accepted for publication 10 July 1978. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-59.

The percentage of postharvest decay caused by Botrytis cinerea (Y) and the percentage of B. cinerea decay at harvest (X) was correlated positively (r = 0.87). The equation Y = 2.47577 + 2.36729 X – 0.02944 X² generated a curve that best fits the date. Apparently healthy mature-green tomato fruits harvested from diseased fields were treated with Botran 75W (DCNA, 3,000–30,000 μg AI/ml) in wax. B. cinerea was controlled for 14 days at 20 C when DCNA residues were 3.3 μg/g of fruit or more. Residues of 2.2–4.9 μg provided good protection against infection by conidia of B. cinerea, with higher residues providing better protection. Lesion diameters (X) on fruits inoculated with mycelial plugs of B. cinerea were correlated negatively (r = –0.81) with the amount of DCNA residues (Y). From the regression equation Y = 31.94799 – 2.91065 X, a residue of 11.0 μg of DCNA per gram of fruit should prevent lesion development. Residues of DCNA between 3.3 and 4.6 μg/g of fruit suppressed the development of established infections, and the number of visible fruit infections was reduced further by higher residues (5.6–12.9 μg).