SURVEYS OF CEREAL DISEASES AND PESTS IN THE NETHERLANDS .3. MONOGRAPHELLA-NIVALIS AND FUSARIUM-SPP IN WINTER-WHEAT FIELDS AND SEED LOTS

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 complied 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 F. culmorum, followed by F. avenaceum and F. 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 16% 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.