NEW RACES OF SUNFLOWER DOWNY MILDEW (PLASMOPARA-HALSTEDII) IN GERMANY

Plasmopara halstedii, the causal agent of downy mildew of cultivated s unflower (Helianthus annuus), was documented in Germany for the first time in commercial fields. The pathogen was first observed in the Wurt temberg area, where races 1 and 4 were identified using a set of diffe rential lines. Later, commercial fields near Baden were found to be in fected by race 5, which is the first occurrence of that race outside o f North America. With the discovery of race 5, there are now eight rac es of the sunflower downy mildew fungus that have been found in Europe . The sunflower cultivars most frequently grown in Germany were invest igated for resistance to race 1, 4 and 5; while all were resistant to race 1, none were resistant to either race 4 or 5.