Evaluation of Herbicides for Common Purslane Control In Turfgrass.

Common purslane (Portulaca oleracea L.) is a summer annual weed that is typically problematic in thin turfgrass or bare soil areas and during establishment of turfgrass. Numerous herbicides are labeled to control purslane in turfgrass, but little published research exists evaluating herbicide effectiveness. Multiple studies were conducted to determine the efficacy of preemergence or postemergence herbicides for controlling purslane in turfgrass. A greenhouse screen of 29 different herbicides was conducted in 2010, to evaluate the postemergence effect on purslane treated at the maximum label rate. Three herbicides, fluroxypyr, triclopyr and simazine, all produced > 90% injury when rated 31 days after treatment (DAT). Carfentrazone, diquat dibromide, and glufosinate all resulted in > 60% injury 10 DAT but recovered to < 30% injury by 31 DAT. Two field studies were conducted in 2011 with nine preemergence  herbicides applied at maximum and ½ maximum label rates to a thin stand of perennial ryegrass (Lolium perenne L.) on 20 April. Eight weeks after treatment (WAT), both rates of isoxaben, simazine, and the high rate of siduron produced < 4% purslane cover. All other treatments produced >20 % purlsane cover and were not different than the untreated control. Twenty seven postemergence herbicides were applied to mature purslane plants on 15 June at the maximum label rate.  By 29 DAT, dicamba, fluroxypyr, and metsulfuron methyl produced < 1% purslane cover and were different from the controls. These 3 herbicides plus aminopyrachlor were the only treatments that showed a continuous decrease in percent purslane cover up through the 29 DAT rating. Both field studies will be repeated in 2012.