Surveys of Foliar Diseases of Spring Barley in England and Wales, 1972–75

Abstract

SUMMARYRandomly selected crops of spring barley in England and Wales were sampled annually in July, when the grain was filling most rapidly, and the diseases affecting the flag and second leaves were assessed. Mildew was the most common disease in all years and was the most severe disease on both leaves, except in 1975 when it was slightly less severe on the flag leaf than yellow rust. Other frequently recorded diseases were brown rust, leaf blotch and, in 1972, 1973 and 1974, Septoria spp. Halo spot and net blotch were infrequent and generally not severe. Fungicides, applied as a seed treatment or foliar spray, were used on up to 47 per cent of the crops assessed and were associated with a decreased severity of mildew. It is estimated that in 1974 and 1975 at least 60 per cent of the crops which received no fungicide would have given an economic yield increase following treatment for mildew control. Annual estimates of national yield losses caused by mildew varied from 5·7 to 13·0 per cent: much greater than the 0·2 to 1·7 per cent estimated for brown rust or leaf blotch. Barley yellow dwarf virus was detected by transmission tests in the majority of the samples tested.