Golf Course Management

OCT 2016

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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10.16 GOLF COURSE MANAGEMENT 97 CUTTING EDGE Teresa Carson Coating warm-season turfgrass seed to improve establishment Saline irrigation of turfgrass has been pro- posed as a water-conservation strategy, but sa- linity can hinder the germination process and be detrimental to turfgrass seedling estab - lishment. A study was conducted in summer 2014 at the University of California-River - side's turfgrass research facility to determine: (1) the effects of five experimental seed coat - ings and Zeba coating on the establishment of Princess-77 bermudagrass and Sea Spray seashore paspalum irrigated with five levels of saline water; and (2) how irrigation salin - ity affects seedling establishment of NuMex Sahara bermudagrass, Whittet kikuyugrass and Sundancer buffalograss. A line-source ex - periment was designed to alternate distribu- tion of potable and saline water to establish an irrigation salinity gradient, identifying five different electrical conductivity (EC) levels (2, 3, 4.5, 5.5 and 7 dS/m). Percent ground cover was assessed weekly using digital image analysis. At three months after seeding, only one seed coating treatment, ASET 4000 6%, had a positive effect on bermudagrass estab - lishment. Compared with uncoated seed, it increased turf cover at 3 and 7 dS/m. ASET 4000 6% coating on Princess-77 had the highest overall turf cover (63%) when irri - gated with saline water at 7 dS/m. Seashore paspalum coated with ASET 4000 1% pro - duced the highest overall cover (97%) at 2 dS/m and had higher turf cover than the un - coated treatment (76% vs. 67%) at 5.5 dS/m. Kikuyugrass was slower to establish under sa - line conditions compared with bermudagrass and seashore paspalum, reaching only 79% cover at 2 dS/m and 0% at 7 dS/m. Buffalo - grass seedling establishment was the slowest and the most affected by irrigation salinity. — Marco Schiavon, Ph.D., and James H. Baird, Ph.D., University of California-Riverside Timing of amicarbazone for Poa annua control Amicarbazone at 0.13, 0.18 and 0.22 pound a.i./acre was initially evaluated to con - trol Poa annua in winter-overseeded perennial ryegrass in February 2010. Sequential appli - cations of the higher rates three weeks apart gave up to 90% control of P. annua for only two months. Following ryegrass overseeding in the fall of 2011, timings of applications in December and January were injurious to the ryegrass when temperatures were very low, and applications of amicarbazone at 0.13 or 0.18 pound a.i./acre were not efficacious against P. annua. In late January to early Feb - ruary 2012, the addition of a non-ionic surfac- tant enhanced the activity of amicarbazone at 0.09, 0.13 and 0.18 pound a.i./acre compared with applications without surfactant added to the spray. In February 2015, applications of amicarbazone at 0.09 and 0.18 pound a.i./ acre showed that the higher rate was visibly more effective against P. annua. A late-spring treatment in May 2015 showed that sequen - tial applications of 0.09 pound a.i./acre pro- vided complete control of P. annua with ac- ceptable ryegrass safety. Amicarbazone at 0.18 pound a.i./acre also provided complete control of P. annua, but the level of ryegrass injury was not acceptable. In the desert, sequential applications of amicarbazone at 0.09 to 0.18 pound a.i./acre applied in early spring (Feb - ruary) with an adjuvant were effective against P. annua and provided adequate safety to the overseeded ryegrass turf. In the photo above, the area to the left of the yellow line was treated with amicarbazone, resulting in brown areas where the P. annua was controlled. — Kai Umeda (kumeda@cals.arizona.edu), University of Arizona, Phoenix Teresa Carson (tcarson@gcsaa.org) is GCM's science editor. Photo by Andrea Feo Photo by Kai Umeda

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