Data from surveys of winter wheat fields in the period 1974-1986 and of seed lots in the period 1962-1986 and identifications of diseases on plant samples were compiled to describe the occurrence of snow mould (Monographella nivalis) and Fusarium spp. On average, M. nivalis dominated over Fusarium spp. The complex of Fusarium spp. constituted mainly of E culmorum, followed by E avenaceum and E graminearum. M. nivalis was dominant in May on stem-bases and in July on leaves and leaf sheaths. On seeds M. nivalis predominated only in years with low temperatures in July and August.Average brown footrot infection in the field was 4% tillers in May and 5~ culms in July. Brown footrot intensity in July was high in cropping seasons with high precipitation in October and with low temperatures in October, November and December. In July during the early eighties, an average of 8 % of leaves and 6% of flag leaf sheaths were infected by M. nivalis. Average ear blight incidence was 1.2% glumes infected. Seed contamination by these pathogens averaged 26% in the years 1962-1986. The contamination was high in years with high precipitation in June, July and August. Aspects of cv. resistance and yield loss are illustrated.
Data of the annual surveys of circa 100 commercial winter wheat fields were compiled to describe epidemics of Septoria spp. in the Netherlands during [1974][1975][1976][1977][1978][1979][1980][1981][1982][1983][1984][1985][1986]. In May, during the first node stage, S. tritici was dominant while S. nodorum was virtually absent. In July, during ripening, S. tritici on average dominated over S. nodorum, though in the most continental districts of the country S. nodorum predominated.In May between 1974 and 1984, on average 56% of the fields showed leaf infections by Septoria spp., while in July between 1975 and 1986, on average 83% of the fields showed leaf infections.Prevalence of Septoria spp. has increased during the surveys. Annual intensity of Septoria spp. in winler wheat crops was positively correlated with precipitation and negatively with average monthly sunshine duration during the harvest month August of the previous growing season. The correlation with sunshine during August could indicate that ascospores play a major role in subsequent epidemics; but whether it is a causal relation remains to be answered.
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