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Postharvest Pathology and Mycotoxins

Nitrogen Nutrition of Tomato Plants and Susceptibility of the Fruit to Bacterial Soft Rot. Jerry A. Bartz, Associate professor of plant pathology, University of Florida, Gainesville, FL 32611; G. M. Geraldson(2), and J. P. Crill(3). (2)Professor of soil science, University of Florida, Agricultural Research and Education Center, Bradenton, FL 33505; (3)Head of the Plant Pathology Department, The International Rice Research Institute, Manila, The Philippines. Phytopathology 69:163-166. Accepted for publication 1 August 1978. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-163.

Incidence of bacterial soft rot following wound inoculation was used to measure the influence of different plant fertilization treatments on the susceptibility of tomato fruit to Erwinia carotovora var. carotovora. The fertilizers were either banded or broadcasted. The susceptibility of the fruit was increased when the banded nitrogen (N) was doubled while the potassium (K) in the band remained constant. No consistent increases in susceptibility occurred, however, when both the N and the K in the band were doubled or when N was applied as broadcasted NaNO₃, NH₄NO₃, Ca(NO₃)₂, or KNO₃. Fruit from the various broadcast treatments were either as susceptible as or more resistant than those from the nonsupplemented N and K treatments. Increased resistance was not consistently associated with any of the supplements. Tissue N, K, and Ca were not correlated with fruit susceptibility. The N and K in the fruit tissue were not correlated with the amounts of those elements applied, but differences in tissue N, K, and Ca were found between treatments. The fruit from the Ca-amended treatments usually had higher Ca.