Monitoring diseases of winter wheat on both a field and a national level in Denmark

Abstract Farmers are provided with simple methods to carry out disease risk assessments in individual fields which enable them to make decisions on the need for fungicide treatment. Assessment of mildew (Erysisphe graminis) and rust (Puccinia striiformis) incidence is on whole plants until growth stage 32 (GS 32). At later stages, assessments are only made on the three upper leaves. Risk of eyespot (Tapesia yallundae) is estimated in spring either using agronomic data, disease incidence or a combination of both. Risk evaluation of the septoria diseases Leptosphaeria nodorum and Mycosphaerella graminicola is based on days with precipitation of more than 1 mm per day and the susceptibility of varieties. In Denmark, the decision support system PC-Plant Protection is used to combine information on thresholds with recommendations for treatments using adjusted fungicide dosages. Weekly reports on disease attack in winter wheat are made on a national level by the Danish Agricultural Advisory Centre. At 55 localities, 2–5 varieties are assessed. This information indicates the general disease situation in the whole country, in different regions and varieties. On a national level, maps are also generated giving accumulated values for precipitation and temperatures. A field monitoring system run in the period 1985–1993 provided actual information on the level of pests and diseases in Denmark, as well as data on yearly variations in the need for fungicide treatments, based on data collected from farmers' field assessments.