Christopher A. Proctor, Roch Gaussoin and Zachary J. Reicher, Agronomy and Horticulture, University of Nebraska Lincoln, Lincoln, NE
Common purslane (Portulaca oleracea L.) is a summer annual weed that is typically problematic in bare soil areas and during turfgrass establishment. Many herbicides are labeled to control purslane in turfgrass, however, little published research exists evaluating herbicide effectiveness. Objectives for this study were to determine the efficacy of preemergence (PRE) and postemergence (POST) herbicides for controlling purslane in turfgrass. Field studies were conducted in 2011 and 2012 at the UNL research facility near Mead, NE. Percent purslane cover was visually determined at 6, 8, 10, and 12 weeks after treatment (WAT) for the PRE studies and at 4, 7, 14, 21, and 28 days after treatment (DAT) for the POST studies. The PRE studies evaluated nine herbicides (Table 1) over three environments (PRE2011, PRE2012a and PRE2012b) at maximum and one-half maximum label rates applied over an immature stand of perennial ryegrass (Lolium perenne L.). Herbicides were applied late March for PRE2012a environment and late April for PRE2011 and PRE2012b environments. No herbicide by rate interaction occurred for any of the PRE environments. There were no treatment differences 6 WAT for any of the environments. Isoxaben and simazine resulted in the lowest percent cover at all rating dates and environments where herbicide differences occurred. Prodiamine was among the treatments with the lowest percent cover at 10 WAT for the PRE2012a environment and at all rating dates for the PRE2012b environment. The POST studies tested 25 herbicides (Table 1) over two environments (POST2011 and POST2012) at the high label rate applied to mature purslane plants in early to mid-June. Diquat dibromide was the only treatment with lowest percent purslane cover 4 DAT for both environments, although fluroxypyr, triclopyr, and several other herbicides resulted in lowest percent cover for the POST2011 environment. Fluroxypyr and triclopyr ranked lowest in percent control at 7, 14, 21 and 28 DAT for both environments and were not different than metsulfuron-methyl, or dicamba 28 DAT. For turf establishment, fluroxypyr, triclopyr, or dicamba applied according to label timing recommendations would effectively control purslane. In areas where seedling safety is not a concern combining a PRE with a POST such as isoxaben and fluroxypyr should provide excellent purslane control.
Table 1. Preemergence and postemergence herbicides used to evaluate common purslane control in turfgrass.