The effect of climatic factors on the activity of isoproturon and clodinafop-propargyl Alopecurus myosuroides (black-grass) in winter wheat

摘要

Field trials were set up at ADAS Boxworth on a clay soil, for two seasons, 1997-1998 and 1998-1999 to assess the activity of the herbicides isoproturon and clodinafop-propargyl on Alopecurus myosuroides in winter wheat. The herbicides were sprayed at4 different rates, on 8 and 10 occasions between 29 October 1997 to 25 February 1998 and 23 November 1998 to 14 April 1999 respectively. There was a considerable variation in the efficacy of the herbicides on the different dates and between seasons, withthe ED50 as a fraction of the recommended dose varying between 0.28 and 1.17 for isoproturon and 0.22 and 1.51 for clodinafop-propargyl. The effects of the weather factors were investigated using multiple regression techniques for the period of 1 to 14days before and after spraying. Significant (p<0.001) regressions were produced for each herbicide in each season, however the climatic factors identified in each season were not the same.