| Abstract/Contents: | "A field study was conducted to measure phytotoxicity and control of bahiagrass seedheads (Paspalum notatum Flugge) with experimental and registered plant growth regulators (PGR's). Research was conducted on an established `Pensacola' bahiagrass turf in Newberry, Florida. The area was mowed 24 hours prior to application of PGR's to insure that seedheads were not present. The study consisted of 3.3 * 3.3 m plots arranged in a RCBD, with 5 replicates and 20 treatments. Treatments and rates were glyphosate, sethoxydim, BAS-514, CGA-16935 1.0, at 0.28 and 0.56 kg ai/ha; fluazifop at 0.112 and 0.28 kg ai/ha, ethofumesate at 1.12 and 2.24 kg ai/ha, maleic hydrazide 3.36 kg ai/ha, sulfometuron 0.0112 kg ai/ha, CGA-16935 2.0 EC at 0.56, 0.672, 0.784, 0.896, and 1.12 kg ai/ha, and an untreated. PGR's were applied with a CO(2) back-pack sprayer calibrated at 187 L/ha. Seedhead production following PGR application was measured by randomly placing a 3.3 m(2) PVC pipe frame within each plot and counting the number of seedheads within the frame. PGR's phytotoxicity effect was visually rated using a 1-9 scale where 6.5 = minimally acceptable and 9 = is best turfgrass color. Data was collected every two weeks and subjected to statistical analysis. Unacceptable phytotoxicity 2 weeks after treatment (WAT) followed glyphosate at 0.56 kg ai/ha, fluazifop at both rates, and sethoxydim at 0.56 kg ai/ha. However, 4 WAT, only glyphosate at 0.56 kg ai/ha had unacceptable turf color and by 9 WAT, all plots were acceptable. Ethofumesate at both rates and BAS-514 at 0.28 kg ai/ha turf color was similar to untreated plots throughout the experiment. Glyphosate at both rates, fluazifop at 0.28 kg ai/ha, sethoxydim at 0.56 kg ai/ha, maleic hydrazide at 3.36 kg ai/ha, sulfometuron at 0.0112 kg ai/ha, and BAS-514 at 0.56 kg ai/ha, had good (greater than or equal to 80%) seedhead suppression compared to untreated plots throughout the study. Conversely, ethofumesate at both rates, BAS-514 at 0.28 kg ai/ha, fluazifop at 0.112 kg ai/ha, CGA-16935 1.0, at 0.28 and 0.56 kg ai/ha, and CGA-16935 2.0 at 0.56, 0.672, 0.784, 0.896, and 1.12 kg ai/ha, had poor (less than or equal to 70%) seedhead suppression throughout the study. Overall, glyphosate at 0.56 kg ai/ha, fluazifop at 0.28 kg ai/ha, sethoxydim at 0.56 kg ai/ha, maleic hydrazide at 3.36 kg ai/ha, and sulfometuron at 0.0112 kg ai/ha were considered the best treatments in that they had more than 80% seedheads control with minimum turf phytotoxicity throughout the 10 week study." |
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