Herbicides with Crop Competition Replace Endophytic Tall Fescue (Festuca arundinacea)

Abstract

Herbicides and interim summer crop treatments were studied in 1984 to 1987 to replace fungal endophyte-infected with endophyte-free tall fescue or red clover to improve forage quality. Foliar glyphosate or paraquat were applied in spring across interim crops with PRE herbicides. The interim crops, grain sorghum with atrazine, sorghum-sudangrass hybrid with metribuzin, or soybean with imazaquin, were each applied as confounded treatments across glyphosate or paraquat. Within an interim crop system, a follow-up glyphosate treatment was serially applied the next fall or spring. Then either red clover or endophyte-free tall fescue was spring drilled within the fall or spring glyphosate follow-up treatments. Glyphosate controlled old tall fescue better than paraquat, and improved the stand of the endophyte-free tall fescue. Control of tall fescue was 97% from 1.7 kg ai/ha glyphosate. Glyphosate reduced the endophyte from a 77% original infection level to 20% over all interim crops after drilling the endophyte-free tall fescue. Among interim crops, grain sorghum or the sorghum-sudangrass hybrid was more competitive than soybean with the uncontrolled tall fescue. Replacement with endophyte-free tall fescue was best in grain sorghum or sorghum-sudangrass hybrid stubble the next spring. Grain sorghum or sorghum-sudangrass hybrid following foliar glyphosate or paraquat treatment of endophyte-infected tall fescue reduced endophyte infection level in tall fescue to 28%. A follow-up fall treatment with glyphosate controlled tall fescue better than the spring retreatment and red clover and endophyte-free tall fescue were established better from fall retreated glyphosate. Red clover was easily established by drilling into the sod after treating endophyte-infected tall fescue with either glyphosate or paraquat.

Herbicide Treatments to Renovate Toxic Endophyte Infected Tall Fescue Pastures with ‘Jesup’ MaxQ

“…This strategy employs a combination of a nonselective herbicide applied in the spring, followed by a summer crop, and then a second application of an herbicide in the following autumn before planting the replacement forage (Bagegni et al, 1994;Roberts and Andrae, 2004). This strategy employs a combination of a nonselective herbicide applied in the spring, followed by a summer crop, and then a second application of an herbicide in the following autumn before planting the replacement forage (Bagegni et al, 1994;Roberts and Andrae, 2004).…”

“…The S-S-S method, as described by Bagegni et al (1994), was employed as an additional control plot. Four additional 3-ha fi elds of E+ Jesup tall fescue (located at the Central Georgia Branch Research and Education Center near Eatonton, GA) also were selected for renovation with Jesup MaxQ.…”

“…Attempts to fi nd conventional herbicide strategies to replace toxic endophyte infected (E+) pastures have had limited success (Hoveland et al, 1986;Smith, 1989;Defelice and Henning, 1990;Bagegni et al, 1994;Prestige and Sprosen, 1995;Washburn and Barnes, 2000). Most of these studies utilized single applications of herbicides to control the grass plants.…”

“…"spray-smother-spray" (S-S-S). This strategy employs a combination of a nonselective herbicide applied in the spring, followed by a summer crop, and then a second application of an herbicide in the following autumn before planting the replacement forage (Bagegni et al, 1994;Roberts and Andrae, 2004). Bagegni et al (1994) found that this strategy gave effi cacious control of E+ and allowed for the replacement of the stand with endophytefree tall fescue.…”

“…This strategy employs a combination of a nonselective herbicide applied in the spring, followed by a summer crop, and then a second application of an herbicide in the following autumn before planting the replacement forage (Bagegni et al, 1994;Roberts and Andrae, 2004). Bagegni et al (1994) found that this strategy gave effi cacious control of E+ and allowed for the replacement of the stand with endophytefree tall fescue. Since the success of an autumn sowing is predicated on adequate moisture, this strategy is costly and risky because the producer commits to the renovation as much as 5 to 6 mo before actual planting (Zhuang et al, 2005).…”