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Estimating Damage to Wheat Caused by Puccinia recondita tritici. J. R. Burleigh, Research Plant Pathologist, Plant Science Research Division, ARS, USDA, Manhattan, Kansas 66502; A. P. Roelfs(2), and M. G. Eversmeyer(3). (2)(3)Research Plant Pathologist, Plant Protection Division; and Research Technician, Plant Science Research Division, ARS, USDA, Manhattan, Kansas 66502 and St. Paul, Minnesota 55101. Phytopathology 62:944-946. Accepted for publication 16 February 1972. DOI: 10.1094/Phyto-62-944.

Disease severities and per cent grain losses from 55 winter and spring cultivar-location combinations were used in a stepwise multiple linear regression computer program to study the relationship between leaf rust severity and yield loss at several wheat growth stages, and to construct general equations to predict crop losses. Coefficients of determination indicated that rust severities at early dough accounted for 64% of the variation in crop loss. However, when severities from boot (X₂), early berry (X₅), and early dough (X₇) were combined in linear regression equations, 79% of the variation in loss was explained. The equation Y = 5.3788 + 5.5260X₂ – 0.3308X₅ + 0.5019X₇ satisfactorily predicted loss (%) with a standard error of 9%. When predicted severities were used in the equation instead of observed severities, the average variation was 8%.