Influence of carrier water and adjuvants on clodinafop-propargyl and mesosulfuron-methyl+iodosulfuron-methyl-sodium+mefenpyr-diethyl efficacy in control of winter wild oat (Avena ludoviciana Durieu

The present study was conducted to investigate the effect of different water hardness levels on the efficacy of clodinafop-propargyl and mesosulfuron+iodosulfuron+mefenpyr-diethyl with and without adjuvants in control of winter wild oat (Avena ludoviciana). The experiment was conducted as a randomized complete block design in factorial arrangement with three replications at the research greenhouse of Iranian Research Institute of Plant Protection during 2017-2019. The experiment factors included herbicides doses at four levels of 25, 50, 75% and 100% of the recommended field rate of each herbicide (the recommended dose for Topik and Atlantis were 64 and 18 g a.i ha-1 , respectively), concentrations of hardness at five levels (0, 250, 500, 750 and 1000 ppm of Calcium bicarbonate) and different levels of ammonium sulfate and urea ammonium nitrate adjuvants at three levels (0, 1 and 2% v/v). The results indicated that the water hardness higher than 500 ppm led to a reduction in the efficacy of clodinafop-propargyl in control of winter wild oat. However, the efficacy of mesosulfuron+iodosulfuron+mefenpyr-diethyl was not influenced by any level of water hardness. According to the results of this experiment, the use of ammonium sulfate 2% or ammonium urea nitrate 1 to 2% reduced the negative effects of hard water containing calcium carbonate with a concentration of more than 500 ppm on the effectiveness of the herbicide clodinafop-propargyl, and reduced the recommended dose of this herbicide by 25 to 50%. Furthermore, the use of ammonium sulfate 2% or urea ammonium nitrate 1% increased the efficacy of mesosulfuron+iodosulfuron+mefenpyr-diethyl.