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Resistance

Equations for Integrating Components of Slow Leaf-Rusting Resistance in Wheat. Gregory Shaner, Associate Professor, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907; F. Dana Hess, Assistant Professor, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907 Phytopathology 68:1464-1469. Accepted for publication 24 April 1978. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-1464.

Equations were developed to help predict how various components of slow-rusting resistance, measured in monocyclic inoculation experiments, interact under field conditions. These equations incorporate the effects of infection efficiency (the number of uredia per 100 spores landing on a leaf), latent period, uredium size, urediospores produced per uredium per day, and infectious period per uredium. In handling latent period data, the equations account for the fact that the infections occurring on a given day erupt into uredia over a period of several days. The equations can be used to predict how certain combinations of slow-rusting resistance components might retard an epidemic. They should be useful to plant breeders as a guide for selecting the most valuable segregants in breeding for slow-rusting resistance.