Use of Penoxsulam As Transition Aid for Perennial Ryegrass Removal in Arizona.

Turf managers in Arizona frequently use herbicides to assist in the spring transition of golf fairways from fall overseeded perennial ryegrass (Lolium perenne) back to a bermudagrass (Cynodon dactylon) turf for the summer. During this transition period a high quality playing surface with good color is desired for aesthetics and playability. Penoxsulam or 2-(2,2-difluoroethoxy)-N-(5,8-dimethoxy[1,2,4] triazolo[1,5c]pyrimidin-2-yl)-6-(trifluoromethyl) benzenesulfonamide)  was compared to a commercial standard for this use in 2012 in small plot research on Arizona golf courses and in 2013 was tested on fairways (larger areas) under an Arizona experimental use permit.

 In the 2012 research trials, penoxsulam was applied as Sapphire® in May and June timings from 2-24 fl oz/A (5.5-66 g ai/ha) to assess impact on both perennial ryegrass and bermudagrass.  Sapphire at 24 fl oz/A was the most effective application rate to remove perennial ryegrass with minimal impact on the bermudagrass at both application timings. The May application resulted in a transition of the turf stand from 100 % perennial ryegrass green tissue to a stand of 80% bermudagrass and 20% perennial ryegrass resulting in a 15% increase in turf quality versus the commercial standard within 36 days.  Sapphire was not observed to inhibit regrowth of bermudagrass when applied at 24 fl oz/A.   Sapphire removal of perennial ryegrass has been shown to be a comparatively smooth and gradual process.  The typically slow perennial ryegrass removal in conjunction with the lack of inhibition of bermudagrass, results in a comparatively stable quality, green turf during transition.

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