ABSTRACT
The activity of difenzoquat against wild oats at two spray volumes, alone or in mixture with other pesticides, was investigated.
In a factorial experiment with three randomized blocks, wild oat grown outdoors in pots was sprayed with four doses of difenzoquat (l,2-dimethyl-3,5-diphenyl-pyrazolium). Difenzoquat was applied either alone or in mixture with 60 g/ha fenvalerate (ct-cyano-3- phenoxybenzyl-α-[4-chlorophenyl]-3-methyl-butyrate); 125 g/ha propiconazole (l-[2-{2,4- dichlorphenyl-4-propyl-l,3-dioxolan-2-yl}-methyl]-lH-l,2,4-triazole); or 60 g/ha fenvalerate plus 125 g/ha propiconazole. All active ingredients were applied as commercial formulations.
The results showed that neither propiconazole nor fenvalerate affected plant growth when applied alone. Hence, the four difenzoquat dose-response curves were assumed parallel when the plant responses were plotted against the logarithm of the difenzoquat dose, and at each spray volume a regression model of plant response on log dose was fitted simultaneously to each dose-response curve. The relative potencies between difenzoquat applied alone or in mixture with different pesticides were independent of the response level considered.
At both spray volumes, propiconazole and propiconazole plus fenvalerate promoted the action of difenzoquat. Fenvalerate, however, did not affect the activity of difenzoquat. In general, the herbicidal effect was enhanced by a reduction in spray volume.
The results are discussed in relation to the different formulations of propiconazole and fenvalerate.
