Potential for the development of reduced sensitivity to DMI fungicides in current control practices for Mycosphaerella graminicola in winter wheat in the UK

摘要

In 1999, over 120 isolates of Mycosphaerella graminicola (Septoria tritici), obtained from throughout England and Wales, were tested to determine their in vitro sensitivity to eight DMI fungicides and to examine cross-sensitivity relationships. Analysis showed positive cross-sensitivity between some of the DMI fungicides tested, with the strongest correlations between cyproconazole, epoxiconazole and flusilazole. In 1998 and 1999, field trials at three UK sites were treated with varying ratios of the DMI fungicides, tebuconazole and epoxiconazole, in mixtures with azoxystrobin. Monitoring the effect of these mixture partners on the sensitivity of M. graminicola to the DMIs showed no shift in sensitivity as a result of selection, regardless of the rates in the mixtures. Some fungicide combinations gave significant yield benefits from improved disease control and extension of the photosynthetic life of the top three leaves.