Frequency of Plant Growth Regulator and Mowing Treatments: Effects on Injury and Suppression of Centipedegrass

Abstract

AbstractCentipedegrass [Eremochloa ophiuroides (Munro) Hack.] is a popular low maintenance turfgrass that produces seedheads from midsummer until early fall, Since regular mowing is needed to maintain a quality turf, experiments on rate and frequency of plant growth regulator applications and mowing frequencies were initiated to assess their effect on suppression of vegetative and reproductive growth of centipedegrass. Various rates of imazethapyr {2‐[4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl‐5‐oxo‐1H‐imidazol‐2‐yl]‐5‐ethyl‐3‐pyridinecarboxylic acid}, mefluidide {N‐[2,4‐dimethyl‐5‐[[(trifluoromethyl)sulfonyl]amino]phenyl]‐acetamide}, and CGA 163935 [4(cyclopropyl)‐α‐hydroxy‐methylene)‐3,5‐dioxocyclohexanecarboxylic acid ethylester] were evaluated as sequential applications and in combination with mowing on suppression of centipedegrass. Imazethapyr applied initially at 0.3 kg ha−1 and then followed by 0.15 kg ha−1 4‐wk later suppressed a higher percentage of centipedegrass seedheads without causing undesirable injury than when the second application was made at a 2‐or 3‐wk interval. Seedhead suppression was similar when imazethapyr was applied at 0.3 kg ha−1 and then followed by two mowings (6 + 8 wk) in 1990 and one mowing (6 wk) in 1991. Mefluidide applied initially at 0.6 kg ha−1 and followed by 0.6 kg ha−1 2‐wk later injured centipedegrass less than when the second application was made at a 3‐ or 4‐wk interval. Seedhead suppression was not consistent each year regardless of the time of the second mefluidide application. However, seedhead suppression was acceptable for 10 wk when mefluidide was applied to 0.6 kg ha−1 and followed by two mowings (4 + 7 wk) in 1990 and three mowings (2 + 4 + 8 wk) in 1991, or when 0.6 kg ha−1 was followed by 0.3 kg ha−1 and one mowing at 6 wk in 1990 and 2 wk in 1991. CGA 163935 injured centipedegrass more and suppressed seedheads less than either imazethapyr or mefluidide.