| Abstract/Contents: | "Tall fescue (Festuca arundinacea), a bunch type perennial grass, is used in the transition zone of the Southern United States, where year-round turf cover is desirable, primarily in home lawns. Crabgrass, however, is a persistent C4 summer annual grass, which effectively competes with the C3 fescue during summer months. The objective of this investigation was to determine the efficacy of commercial and experimental herbicides for crabgrass control in turf type tall fescue. Two studies were conducted at Clemson, University. Study one investigated the treatment efficacy of commercially available chemicals including Pendulum (Pendimethalin), Surflan (Oryzalin), Ronstar (Oxadiazon) and three experimental formulations of dithiopyr designated as MON-29882, MON-58430, and MON-8459. Study two investigated the efficacy of Dimension (Dithiopyr), Pendulum (Pendimethalin), Barricade (Prodiamine) and various rates of experimental herbicides designated as XF-00090, XF-00091, XF-00272, XF-01005 and SARS-295. The experiments subjectively determined the control of smooth crabgrass (Digitaria ischaemum) on a percentage scale with 100% designated as total control. Both studies were designed in a randomized complete block arrangement with individual plots measuring 1.5 m x 2.0 m replicated three times. Plots were mowed to simulate a home lawn and maintained at 2.5 inches. Treatments were applied using a CO2 backpack spray boom or granular shaker-can depending on herbicide formulation. Treatments for study one were applied on March 13 with a sequential application on May 8. Treatments for study two were applied on March 13, April 24, and May 8. For each study, ratings were taken between June and August at 90, 102, 120, 150 days after the initial application. In study one, Pendimethalin at 3.0 lb ai/A, split applications of Pendimethalin at 1.5 lb ai/A, split applications of Surflan at 1.5 lb ai/A, and one application of Surflan at 3.0 lb ai/A provided greater than 90% control throughout the study. MON-58430 at 1.83 lb ai/A followed by a sequential application of 0.92 lb ai/A provided 75% throughout the study. In study two, five formulations of the XF herbicides [0.164 G (0.25 lb ai/A), 0.25 G (0.38 lb ai/A), 2.5 SC (0.25 lb ai/A), 2.5 SC (0.38 lb ai/A), 2.0 SC (0.38 lb ai/A)] were successful (>90%) at controlling crabgrass throughout the study. Additionally, Dimension [1EC (0.38 lb ai/A), 40 WP (0.38 lb ai/A)], Pendulum [3.8 CS (1.5 lb ai/A X 2), 3.8 CS (3.0 lb ai/A), 3.3 EC (1.5 lb ai/A X 2), 3.3 EC (3.0 lb ai/A), 2 G (3.0 lb ai/A)], Barricade [65 DF (0.38 lb ai/A X 2), 65 DF (0.5 lb ai/A)], also controlled crabgrass at greater than 90%. Future research in this area may include experimentation with additional herbicides. Further, it is necessary to investigate more rates and timings with the herbicides utilized in this study to maximize crabgrass efficacy while insuring the integrity of the tall fescue." |
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