Golf Course Management

FEB 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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02.16 GOLF COURSE MANAGEMENT 99 Aug. 12, 2014. These plants were uninjured from halosulfuron at a standard use rate, 1.3 ounces/acre (91 grams/hectare), applied ap - proximately three weeks before collection. Annual sedge was also collected in Griffn, Ga., from a susceptible population. The two biotypes were grown out in a greenhouse at the University of Georgia-Griffn campus. Upon maturity, seeds were collected by hand and scattered with soil (85 sand:15 peat moss) over pots 1.5 inch (3.8 cm) in diameter and 7.87 (20 cm) inches deep. Pots were fertigated (MacroN 28-7-14 sprayable fertilizer, Lesco) biweekly and allowed to reach a height of 4 inches (~10 cm) before treatments. The response of the two annual sedges was evaluated from a rate titration of halosulfuron (Sandea, Gowan Co.). Treatments were ap - plied in a rate titration ranging from 0.1 to 20.8 ounces of product per acre (4.4 to 1,120 grams ai/hectare). Nontreated checks of the two biotypes were included. A non-ionic sur - factant (Chem Nut 80-20, a mixture of alkyl and alkylaryl polyoxyethylene glycol, 80%; Chem Nut Inc.) was added to the spray so - lution at 0.25% volume/volume. Plants were returned to the greenhouse about one hour after treatment and did not receive irrigation for 24 hours. After eight weeks, the halosulfuron rate re - quired to reduce dry shoot biomass 50% mea- sured 0.14 ounce/acre (8 grams ai/hectare) for the susceptible biotypes and more than 21 ounces acre (>1,120 grams ai/hectare) for the resistant biotypes. All application rates of halo - sulfuron reduced biomass of the resistant bio- type less than 12%. Halosulfuron rates equal to or greater than 0.67 ounce/acre (35 grams ai/hectare) reduced biomass of the susceptible biotype more than 80%. Results support the supposition that the resistant annual sedge biotype could tolerate halosulfuron levels 140 times greater than those tolerated by the sus - ceptible biotype. Green ouse experiment 2 In a separate greenhouse experiment, an - nual sedges were treated with various herbi- cides, including glufosinate (Finale, Bayer), glyphosate (Roundup, Monsanto), halosulfu - ron (Sedgehammer, Gowan), imazapic (Pla- teau, BASF), mesotrione (Tenacity, Syngenta), MSMA (Target 6, Luxembourg-Pamol), sulfentrazone (Dismiss, FMC Professional So - lutions), sulfosulfuron (Certainty, Monsanto) and trifoxysulfuron (Monument, Syngenta). In this feld experiment, MSMA was shown to be effective in controlling an ALS-resistant annual sedge. Figure 1. Biomass reductions for ALS-resistant and ALS-susceptible biotypes of annual sedge at eight weeks after treat- ment in greenhouse experiments. The herbicides evaluated were: glufosinate (Finale 1 L, Bayer), glyphosate (Roundup Pro, Monsanto), halosulfuron-methyl (Sandea/Sedgehammer, Gowan), imazapic (Plateau, BASF), MSMA (Target 6 L, Luxembourg-Pamol), sulfentrazone (Dismiss, FMC), sulfosulfuron (Certainty, Monsanto) and trifoxysulfuron-sodium (Monu - ment, Syngenta). All herbicides were applied with a non-ionic surfactant at 0.25% volume/volume, except glyphosate. LSD = least signifcant difference. Biomass reductions Halosulfuron Imazapic Sulfosulfuro n Trifloxysulfuron Glyphosate Glufosinate Sulfentrazone MSMA -20 0 20 40 60 80 100 Resistant Susceptible LSD=21 Shoot mass reduction (% of nontreated)

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