Effect of herbicide treatments on the weed mass in a long-term experiment in Martonvásár

Abstract

The weed mass (g m -2 ) recorded in the first 15 years (1965)(1966)(1967)(1968)(1969)(1970)(1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)) of a long-term, bifactorial, split-plot herbicide experiment (main plots: two types of soil cultivation, subplots: 7 herbicide treatments, with two control plots) without crops indicated that the best weed control was achieved with 10 kg ha -1 rates of simazine and atrazine. These were followed by 5 kg ha -1 ametryn, 10 kg ha -1 linuron and 2+2 kg ha -1 2,4-D, all with moderate efficiency, while 5 kg ha -1 prometryn and 10 kg ha -1 monolinuron resulted in poorer weed control. Medium deep ploughing once a year in autumn reduced the weed mass by 36.5%. There was a substantial year effect, well illustrated by the annual changes in weed mass both in the herbicide treatments and in the control plots. In plots treated with simazine and atrazine there was an exponential increase in the weed mass from the 17 th year of the experiment, suggesting the multiplication of weed biotypes resistant to triazine. As a result of some herbicide treatments there was a shift in the monocot-dicot ratio.