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Disease Detection and Losses

Quantifying Cephalosporium Stripe Disease Severity on Winter Wheat. W. W. Bockus, Assistant professor, Department of Plant Pathology, Kansas State University, Manhattan 66506; T. Sim IV, survey plant pathologist, Division of Entomology, Kansas State Board of Agriculture, Topeka 66612. Phytopathology 72:493-495. Accepted for publication 14 July 1981. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-493.

Four methods and times of quantifying Cephalosporium stripe disease severity were compared utilizing four winter wheat (Triticum aestivum) cultivars each inoculated at five different levels. Of the four disease-rating systems, only percentage of infected tillers or a disease severity scale based upon degree of systemic symptom expression caused by Cephalosporium gramineum were highly correlated with yield losses due to stripe. Both types of rating systems gave reliable estimates of yield loss only if taken at growth stages 10.0 or 10.5 on the Feekes’ scale. Percentage of infection/yield loss curves were linear, but could not be used to directly compare data between years since the slope of the line changed from year to year. Disease severity/yield loss curves also were linear, but the slope of the line did not change significantly between years.