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Disease Detection and Losses

Development and Evaluation of a General Model for Yield Loss Assessment in Potatoes. D. Shtienberg, Department of Plant Pathology, 334 Plant Science Building, Cornell University, Ithaca, NY 14853, Present address: Hebrew University of Jerusalem, Faculty of Agriculture, Department of Plant Pathology and Microbiology, P.O. Box 12, Rehovot 76100, Israel; S. N. Bergeron(2), A. G. Nicholson(3), W. E. Fry(4), and E. E. Ewing(5). (2)(4)Department of Plant Pathology, 334 Plant Science Building, Cornell University, Ithaca, NY 14853; (3)(5)Department of Vegetable Crops, 151 Plant Science Building, Cornell University, Ithaca, NY 14853. Phytopathology 80:466-472. Accepted for publication 28 November 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-466.

A general model for yield loss assessment in potatoes was developed and parameterized for early blight and late blight. Disease-induced losses for any given crop are predicted relative to a reference crop. Loss is a function of the difference in the relative area under the disease progress curves (RAUDPC) among these crops multiplied by the effect of disease on bulking rate. RAUDPC calculation is based on integrating disease severity over the period of yield accumulation and weighing each chronological day by its relative contribution to host growth. Seventy-one epidemics of early blight or late blight that developed in Freeville, NY, where the model?s parameters were estimated, and 53 epidemics from other growing areas or from epidemics having both pathogens simultaneously in Freeville, NY, were used as independent data sets for evaluating the predictions of the model. Differences between predicted and observed losses ranged from ?11.2 to 8.1% and were less than 5% in 80% of the cases.

Additional keywords: Alternaria solani, Phytophthora infestans.