Response of Seven Woody Ornamentals to Turfgrass Herbicide Applications of Arylex, Penoxsulam, and Pyrimisulfan

With the recent stop-sale and distribution by the EPA in 2011 of aminocyclopyrachlor for use in turfgrass systems due to reported tree harm, many newly registered turfgrass herbicides are intensely tested for ornamental damage. New herbicides that have shown effective weed control in turfgrass systems are arylex, penoxsulam and pyrimisulfan. The objective of this study was to investigate the influence of turfgrass applications of arylex, penoxsulam and pyrimisulfan herbicides on seven common woody ornamental landscape species. Research trials were initiated on a nursery production facility at the Tuttle Forestry Research Center in Manhattan, KS. Seven ornamental species were tested included; blue spruce (Picea pungens ‘Glauca’), eastern redbud (Cercis canadensis), red maple (Acer rubrumn ‘Sun Valley’), burr oak (Quercus macrocarpa), elm (Ulma parvifolla ‘Frontier’), viburnum (Viburnum x rhytidophylloides ‘Allegheny’) and limber pine (Pinus flexilis ‘Vanderwolf’s Pyramid’). Individual species were grown 19 L nursery pots. Herbicide treatments included; pyrimisulfan (0.18 kg ai ha^-1), pyrimisulfan (0.36 kg ai ha^-1), pyrimisulfan (0.18 kg ai ha^-1) + penoxsulam (0.18 kg ai ha^-1), pyrimisulfan (0.27 kg ai ha^-1) + penoxsulam (0.27 kg ai ha^-1), aminocyclopyrachlor (1.52 kg ae ha^-1), arylex (0.02 kg ae ha^-1)+ fluoxypyr (0.32 kg ae ha^-1) + dicamba (0.28 kg ae ha^-1), arylex (0.02 kg ae ha^-1) + fluoxypyr (0.3 kg ae ha^-1) + 2,4-D (2.2 kg ae ha^-1), 2,4-D (2.67 kg ae ha^-1) + MCPP (0.71 kg ae ha^-1) + dicamba (0.24 kg ae ha^-1) and a non-treated control. Treatments were applied 3 August 2015 and arranged as randomized complete design with three replications within each species. Liquid herbicide treatments were applied in 8 fl oz of water to the soil surface of each individual species. Granular treatments we applied to soil surface by hand then watered in with 8 fl oz. All treatments were applied to simulate common turfgrass application. Visual phytotoxicity (0% - 100% scale) was conducted monthly throughout the experiment. Data were subjected to ANOVA in SAS and means were separated according to Fisher’s Protected LSD at p=0.05. No injury was observed on blue spruce, limber pine and red maple regardless of treatment throughout the experiment. Unacceptable injury was observed by aminocyclopyrachlor applications at 0 – 57 DAA (days after application) on eastern redbud, elm and viburnum. High Pyrimisulfan + penoxsulam rates at 57 DAA also resulted in slight <40% elm phytotoxicity, significantly greater than non-treated. Results indicate high herbicide safety on select landscape ornamentals of developing turfgrass herbicides.