Use of Pyrimisulfan and Penoxsulam in Turfgrass Systems.

Pyrimisulfan and penoxsulam are acetolate synthase (ALS) inhibiting herbicides utilized for weed control in turfgrass systems. Research trials in 2014 through 2016 in Kansas were conducted to further explore pyrimisulfan and penoxsulam use in turfgrass systems and safety to non-target landscape vegetation.  Research trials were initiated in Junction City, KS on September 14, 2014 to evaluate post-emergent yellow nutsedge (Cyperus esculentus) and spotted surge (Euphorbia maculata) control with pyrimisulfan and penoxsulam combinations. In May 2016 research trials in Manhattan, KS were initiated to determine pre-emergent large crabgrass (Digitaria sanguinalis) control with pyrimisulfan and penoxsulam. Pre-emergent treatments included; pyrimisulfan (45 g ha^-1), pyrimisulfan (90 g ha^-1), pyrimisulfan [45 g ha^-1 followed by (fb) 45 g ha^-1 60 days after initial treatment (DAIT)], pyrimisulfan + penoxsulam (90 g ha^-1), pyrimisulfan + penoxsulam (180 g ha^-1) and pyrimisulfan + penoxsulam (90 g ha^-1 fb 90 g ha^-1 60 DAIT). Additional pyrimisulfan + penoxsulam treatments were applied at same rate on a nitrogen fertilizer carrier. ‘Cody’ buffalograss (Bouteloua dactyloides) and ‘Meyer’ zoysiagrass (Zoysia japonica) tolerance studies were initiated on May 5, 2016 in Manhattan, KS to evaluate tolerance during spring transition with pyrimisulfan and penoxsulam applications.  Treatments included pyrimisulfan and penoxsulam applied at 70, 105, 140 g ha^-1 and pyrimisulfan + penoxsulam at 70, 140, 210 and 280 g ha^-1. In 2015 and 2016 research trials were conducted to determine ornamental species tolerance to turfgrass pyrimisulfan and penoxsulam applications. All treatments within each trial included a non-treated control and were arranged in a randomized complete block with 3 or 4 replications. Analysis of variance was performed in SAS and means were separated according to Fisher’s Protected LSD at 0.05 significance level.  Pyrimisulfan + penoxsulam at 180 g ha^-1 resulted in excellent pre-emergent large crabgrass control, 90 DAIT.  No buffalograss, zoysiagrass, or ornamental injury was observed throughout tolerance studies.