Crop Losses Caused by Xanthomonas Streak on Spring Wheat and Barley. W. W. Shane, Department of Plant Pathology, Ohio State University, Columbus 43210-1087. J. S. Baumer, and P. S. Teng. Land O'Lakes Research Farm, R.R. 2, Webster City, IA 50595; and Department of Plant Pathology, University of Minnesota, St. Paul 55108. Plant Dis. 71:927-930. Accepted for publication 20 February 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0927.

The relationship between severity of Xanthomonas streak and yield components of spring wheat was evaluated for plots and modified single tillers (MST). In the MST approach, tillers with similar disease severities were harvested and processed in bulk lots of 10 tillers. In three seasons, a 50% disease severity on the flag leaf resulted in an 8–13% loss in kernel weight; a 100% disease severity on the flag leaf resulted in a 13–34% loss. Disease onset was too late to affect the number of kernels per head. Protein concentration in the grain was positively correlated with disease severity in most years. The MST approach was deemed more efficient than single-tiller or plot methods for determining severity/loss relationships for this disease.