Surveys of cereal diseases in Northern Ireland, 1976 to 2000

Abstract

A number of disease surveys was carried out on the three main cereals grown in N. Ireland from 1976 to 2000, namely spring and winter barley and winter wheat. Although not all crops were surveyed in each year, the surveys provide a good picture of changes in disease spectra over the years. The most dramatic change in spring barley disease has been the almost complete disappearance of Blumeria graminis (mildew) and its replacement as the dominant disease by Rhynchosporium secalis (leaf blotch). Leaf-spotting ascribed to physiological causes also became more common in the latter years of the surveys. The disease spectrum of winter barley was more consistent from year to year, with Rhynchosporium secalis as the most common pathogen. Barley yellow dwarf virus was relatively severe in 1984, but in no other years. In winter wheat, there was a major change with the almost complete eclipse of Phaeosphaeria nodorum leaf blotch by Mycosphaerella graminicola (septoria tritici blotch). Gaeumannomyces graminis (take-all) was frequently severe. Surveys of cultivar popularity generally showed a rapid change in varieties over a relatively short time. Surveys of fungicide usage tended to show an increase in numbers of sprays applied, in spite of the fact that commercial pressures should have been acting towards a reduction in spraying.