Effects of some adjuvants on 2,4-D+MCPA, bromoxynil octanoate + MCPA + ethylhexyl ester, tribenuron methyl, bentazone + dichlorprop efficacy in dandelion (Taraxacum officinale) control in bermuda grass lawn (Cynodon dactylon)

A split-factorial experiment was conducted in a randomized complete block design with three replications in a landscape of Qom in 2018. The main factor was the time of herbicide application in spring and summer and sub-factors were factorial combination of 1052.5 g ai.ha-1 2,4-D+MCPA (U46 Combi Fluid, SL 67.5%), 600 g ai.ha-1 Bromoxynil octanoate + MCPA + ethylhexyl ester, 15 g ai.ha-1 tribenuron methyl, and 1132 g ai.ha-1 bentazone + dichlorprop and 0.3% of dioctyl sulfosuccinate sodium salt and oleic acid ethoxylate adjuvants and ammonium sulfate (VI) and the control treatment. Results showed that although some treatments caused an effective loss in dandelion dry weight, they also caused severe damage to the lawn. Mixing oleic acid ethoxylate or sodium sulfosuccinate with ammonium sulfate with bentazone + dichloroprop in the spring resulted in the reduction of the dry matter of dandelion from 337 in the control treatment to 81.6 and 100 g.m-2, respectively. Also, mixing oleic acid ethoxylate and ammonium sulfate with tribenuron methyl in summer reduced dandelion dry matter from 298 in the control treatment to 113 g.m-2, which had the least damage to the grass compared to other treatments.