Assessment of Loss caused by Barley Mildew using Single Tillers

SUMMARY A method for estimating losses due to foliar diseases with more precision, using little space and time and without the need for artificially producing different levels of disease, is described. Randomly selected tillers were labelled with their mildew level on leaf 2 at growth stage 10.5 and the ripe ears harvested to obtain values for seed number, seed weight and yield for each ear. Regressions of all three parameters on mildew level were negative and highly significant. Converted to per cent loss equations the mean regression coefficients for cvs. Ymer and Golden Promise were:—seed weight on mildew, 0·257; seed number on mildew, 0·291; and yield/ear on mildew, 0·498. There was no evidence of non-linearity in the response of yield loss to mildew.