Relationship between scald (Rhynchosporium secalis) and losses in grain yield of barley in Western Australia

Abstract

The three commonly used techniques, viz. critical point model, area under the curve and multiple linear regression, were applied to study the relationship between scald infection and grain yield in field experiments conducted during 1979-1983 in Western Australia. In the preliminary analysis leaf three from the top and the mean of the top three leaves were found to be best correlated with yield. The three models did not dilfer greatly, presumably owing to the high correlations between scald at the milky ripe stage and at the earlier growth stages. The critical point model was chosen because of its simplicity. Percentage yield loss in combined data from all experiments showed a significant correlation (P < 0.001) with scald at the milky ripe stage and defined percentage yield loss in cultivars Clipper and Stirling to be about one-third of the mean scald damage on leaves 1 (flag), 2 and 3 at g.s. 75. Due to the range of trials in this analysis, it was suggested that this relationship may be applied to estimate yield loss from survey data in other parts of southern Australia, where scald is endemic.