| Abstract/Contents: | "Cool-season perennial grasses (C3PG) are currently being evaluated for the southern Great Plains, since these grasses can provide high quality forage when the dominant warm-season grasses are dormant and these grasses could have an advantage over the current annual cool-season forages like rye (Secale cereale), and ryegrass (Lolium multiflorum) (RG) since the annual grasses have to replanted each year and are exposed to environmental (rainfall) risks associated during the establishment period. However, establishment of these perennial grasses has been unsuccessful, especially where cool-season annual grasses are prevalent. The objective of this paper is to summarize research trials (PRE herbicide screening, POE herbicide screening, Seed treatments, Banding herbicides, and Vegetation management (glyphosate timing applications and planting dates) to determine the best method for establishing summer dormant tall fescue (Festuca arundinacea) (SDF), summer active tall fescue (SAF), tall wheatgrass (Thinopyrum ponticum) (TWG), and hardinggrass (Phalaris aquatica) (HG) in traditional graze-out systems containing RG. PRE Herbicides: SDF, SAF, TWG, and HG were drilled with Hege planter in fall of 2005 at the recommended seeding rates and diclofop, diuron, metolachlor, trifluralin, metribuzin, and atrazine were applied immediately after planting at the recommended rates. All herbicide treatments severely injured or killed SDF, SAF, and HG. Diclofop, diuron, metribuzin, and atrazine caused little injury to TWG, however only diclofop and diuron provided control of RG, therefore these PRE herbicides should be further evaluated for establishing TWG. POE Herbicide Screening: Fifteen herbicides were applied in 2004 and 2005 when a majority of the perennial grasses reached the 5-leaf stage. Herbicides were not selective between SDF, HG, and RG; herbicides that controlled RG also killed these grasses. In 2004, Nicosulfuron and clodinafop provided acceptable control (>85%) while injuring SAF by ~70%, however, SAF recovered by the end of the growing season and had 70% stand for both herbicides. Diclofop, clodinofop, and mesosulfuron controlled RG (>85%) and caused no injury to TWG, and had 80% stand at the end of the growing season, therefore these POE should be considered when establishing TWG. Seed Treatments: SDF seeds were treated with Concep seed safener, Dynasty fungicide, or activated charcoal at 250%, 500%, and 750% buildup and drilled with Hege planter in the fall of 2004. Recommended use rates of diuron, trifluralin, imazapic, diclofop, and metolachlor were applied immediately after planting before emergence. Although the 750% activated charcoal reduced injury with all herbicides, all herbicide-seed treatment combinations caused excessive injury to tall fescue. Thus it appears that these seed treatments do not appear useful. Banding Herbicides: In 2004, SDF was seeded to moisture using a Hege No-till drill. Diuron and imazapic were banded on 40, 60, and 80% of the area between the rows. Both 40 and 60% caused no injury and resulted in excellent stands (>95% cover). In 2005, diuron, imazapic, metolachlor, metribuzin, and atrazine were banded on 60% of the area when SDF, SAF, TWG, and HG were planted with a clean-till drill. Results in 2005 were extremely variable due to limited moisture conditions at the time of planting. Seeds planted to moisture, germinated and there was no visible injury, however a majority of the seeds did not germinate prior to the next rainfall, which resulted in movement of the herbicide into the row and prevented emergence. Banding may have potential, however due to dependence on drilling to moisture and seeds germinating before it rains, it is unlikely to be widely used. Applying these PRE herbicides POE to the crop may be a better option. PRE Herbicides applied POE: In 2005, diuron, metolachlor, atrazine, metribuzin, and trifluralin were applied to SDF, SAF, TWG, and HG at the 3-leaf and 5-leaf stage. Diuron controlled SDF and HG and were safe on SAF and TWG. Atrazine and metribuzin controlled HG, but were safe on SDF, SAF, and TWG. Metribuzin and trifluralin did not cause visual injury to any of the grasses evaluated. Vegetation Management (glyphosate timing): In both 2004 and 2005, the best method for establishing these cool-season perennial grasses in fields known to have annual grassy weeds was a combination of spring-applied glyphosate in May to prevent seed production followed by another glyphosate application after weeds emerge following rainfall in autumn (which occurred in Oct both years), and no-till drilling seed to moisture. In 2004, this treatment averaged 4673 kg/ha for C3PG and 1297 kg/ha for RG, at the end of the growing season. In 2004, grazing did not change species composition or improve establishment of the perennial cool-season grasses evaluated." |
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