Surveys of Foliar Diseases of Spring Barley in England and Wales 1967‐ ‐ 70

SUMMARY Samples from 250–300 spring‐sown barley crops including all popular cultivars were taken when the grain was milky ripe. The percentage of the leaf area affected by recognizable diseases was recorded for the top two leaves and sub‐samples were tested for barley yellow dwarf virus. Mildew was the most severe disease in the first three years. In 1970, brown rust was most severe. Leaf blotch was the second most severe disease in 1969; in other years it was less severe than mildew and brovm rust. Estimated losses in yield due to mildew were revised in the light of recent data on disease progress. Annual losses of 7–11 per cent, with a mean over the four years of 9 per cent were estimated. Losses caused by leaf blotch infection were estimated to have been about 1 per cent in 1967, 1968 and 1969 and nil in 1970. No consistent annual pattern of distribution of mildew between geographical regions was apparent. Brown rust and leaf blotch infection levels tended to decrease from south to north. Disease severity was related to previous cropping only with respect to leaf blotch in 1969 when crops following a previous barley crop were infected more severely than those following another crop.