INTERRELATIONSHIP BETWEEN INCIDENCE AND SEVERITY OF LEAF STRIPE ON BARLEY
M.I.E. Arabi, M. Jawhar
Leaf stripe caused by Pyrenophora graminea has been the major yield-reducing factor for barley production during the last decade. In this study, the relationship between incidence (I; proportion of diseased plants) and severity (S; proportion of infected leaf area per plant) for leaf stripe of barley was investigated. Disease assessments were made visually at multiple sample sites in artificially and naturally inoculated research and production fields during four growing seasons. Significant differences (P = 0.05) in mean I and S values were found among cultivars, with values being consistently higher in the susceptible ones. However, leaf stripe severity increased linearly as incidence increased. The slopes and intercepts of the I–S relationship were consistent over the four growing seasons. The information obtained from this study is valuable for leaf stripe assessment which can substantially reduce the work load in disease quantification in field surveys and enable to select the resistant cultivars early in breeding programme.