Germination of the cleistothecium of Blumeria graminis on wheat and its establishment of sensitive base line to triadimefon

Cleistothecia of powdery mildew were collected from the mountainous areas in Lichuan of Hubei where never used fungicides of demethylation inhibitor to control wheat disease. Sixty one single pustule isolates were gained by infected leaf segments with ascospores from different cleistothecia. The EC 50 of triadimefon to every isolate on the detached leaf segments was determined in laboratory and the average EC 50 was (0 109 0±0 004 8) μg/ml. It was thought as sensitive base line of the Blumeria graminis f. sp. tritici to triadimefon.