Evaluation of newly established buffalograss for tolerance to glyphosate

Abstract

Buffalograss [Buchloe dactlyoides (Nutt.) Engelm.] is gaining popularity as a turfgrass for low maintenance sites, where irrigation and regular mowing or fertility may not be available. Unfortunately, weed species also thrive in low maintenance sites. This field study was conducted to assess the utility of glyphosate as a selective herbicide in newly established buffalograss. Buffalograss (cultivar Cody) burs were sown into newly renovated sites in Fayetteville, AR, in the summer of 2017 and 2018. Glyphosate was applied at 1, 3, and 8 weeks after emergence (WAE) of buffalograss seedlings at rates of 0.15, 0.325, 0.75, 1.5, 3.0 lb a.e. acre–1 of glyphosate and one untreated control. These rates correspond to 0.1 time (×), 0.25×, 0.5×, 1.0×, and 2.0× of the highest labeled rate of 1.5 lb a.e. acre–1 of glyphosate (64 fl oz acre–1, RoundUp Pro, Bayer Cropscience). Following application, plots were assessed using visual ratings of turf quality on a 1–9 scale at weekly intervals for 10 weeks. One week after applications at 8 WAE, images were taken of each plot and analyzed for dark green color index (DGCI) as a quantified measure for the green value of living foliage in treated areas. In both years and all application timings, buffalograss turf quality was reduced to an unacceptable quality when treated with glyphosate at 0.25× of the maximum labeled rate and above. At the 0.1× rate of glyphosate, buffalograss turf quality was not significantly reduced in either year at any application timing.