Full TGIF Record # 13797
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Publication Type:
Content Type:Abstract or Summary only
Author(s):DeFelice, Michael S.; Brown, William B.; Perkins, Cheryl S.
Author Affiliation:Department of Agronomy, University of Missouri, Columbia, MO
Title:Using Herbicides for No-tillage Renovation of Endophyte Infected Tall Fescue Pastures.
Meeting Info.:|d December 8-10
Source:Proceedings of the North Central Weed Control Conference. Vol. 42, 1987, p. 71.
Publishing Information:Omaha, NB
Keywords:TIC Keywords: Herbicides; Festuca arundinacea; Endophytes
Abstract/Contents:"Research has shown that the endohytic fungus Acremonium coenophialum present in most tall fescue (Festuca arundinacea Schreb. 'Kentucky 31') pastures has a detrimental effect on livestock. The fungus reduces the efficiency of weight-gain and causes reproduction problems. There are several potetial solutions to the endophyte problem. One would be to increase the amount of other feed sources in the diet to reduce the amount of endophyte infected fescue forage and hay in the diet. Another widely proposed solution would be to replace the infected pastures with another forage such as alfalfa, warm-season grasses or an endophyte-free fescue. The Missouri Department of Natural Resources and the Soil Conservation Servece started a cost share program in 1985 to assist farmers who wished to replace endophyte infected tall fescue pastures with another forage species or endophyte free fescue. At that time, the program required that the new pasture species be no-till planted directly into the killed fescue sod and did not allow the use of an interim intercrop planting. These limitations required that the use of herbicides and direct no-till drilling of endophyte free fescue seed would be necessary if fescue was the desired final pasture. A study was initiated at the Bradford Agronomy Research Farm in Columbia, MO in October of 1985 to evaluate the use of herbicides to kill endophyte infected tall fescue and replace it with endophyte free tall fescue using no-till methods. The study was repeated in the fall of 1986. Herbicides were applied in the fall, fall and spring and in the spring to evaluate their efficacy for killing tall fescue. This fall/spring program required planting tall fescue in the spring. After 1.5 years all plots were sampled and tested for final endophyte infection levels. Each plot was sampled at ten random locations with three fescue leaf sheaths collected for each sample. The sheath epidermis of each plant was stained with aniline blue and examined under a microscope to determine the presence of the endophyte fungus. A sample site was considered infected if any one of the three leaf sheaths taken from that sample were infected. Final infection level was expressed as the percent of the ten sample sites that were infected in each plot. Each treatment was replicated four times in a randomized complete block design. Herbicide treatments were applied with a CO2 backpack sprayer using flat fan nozzles. Treatments were applied in a spray volume of 187 1/ha (except glyphosate which was applied at 93.5 1/ha), at a spray pressure of 163 kpa at the boom. Each plot was 2 m wide by 9 m long. The test area mowed to a height of 7 to 10 cm 3 days prior ro spraying paraquat. The glyphosate and sethoxydim treatments were applied 14 days later to 15 to 20 cm fescue at the same time the paraquat sequential treatments were applied. Herbicide rates evaluated were .53 kg/ha of paraquat, .42 and .84 kg/ha of glyphosate and .45 kg/ha of sethoxydim. Percent fescue kill was visuallyevaluated 2, 4, and 6 weeks after application and a final rating was made in April of each year before the new endophyte free fescue had become established. Endophyte free tall fescue var. 'Martin' was planted at a rate of 22 kg/ha in late March of each year. A summer study was also established in 1986 and 1987 to evaluate the efficacy of herbicides applied in August with immediate planting of endophyte free fescue in early September. Most of the paraquat and glyphosate treatments applied in the fall, fall + spring and apring gave 75 to 90 visual kill when evaluated in the spring. The .42 kg/ha rate of glyphosate applied in the fall was not as consistent as the .84 kg/ha rate. The paraquat required a sequential application of .53 kg/ha to achieve initial control levels above 80%. The Fall + 14 day treatments were better than the Spring + 14 day treatments. Sethoxydim did not give acceptable fescue kill in either year of the experiments. Final endophyte infection levels are only available for the first year of the study at this time. There was no significant reduction in endophyte infection level with any of the treatments tested in the fall/spring study. The initial infection level in the test area was 90%. The final infection levels were in a range of 55 to 90%. Initial results and observations indicate that the original Kentucky 31 fescue re-established itself by growing from the underground rhizomes of the treated plants. In the summer treatment study only the 1.68 and 2.5 kg/ha rates of glyphosate gave good initial visual kill. These two treatments also significantly reduced endophyte infection levels to an average of 25 % from the initial 85% infection level in the test area. The paraquat treatments applied in August did not significantly reduce infection levels."
Note:This item is an abstract only!
ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
DeFelice, M. S., W. B. Brown, and C. S. Perkins. 1987. Using Herbicides for No-tillage Renovation of Endophyte Infected Tall Fescue Pastures.. Proc. North Cent. Weed Sci. Soc. 42:p. 71.
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