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Chemical Options for Selective Control or Suppression of Bermudagrass in Creeping Bentgrass, Kentucky Bluegrass, and Perennial Ryegrass
| Description: | |  |
| Author: | S. D. Askew, J. B. Beam, W. L. Barker, and E. H. Ervin |
| Author Org: | Virginia Tech |
| Date: | 01/27/2004 |
| Presenter: | S. D. Askew |
| Conference: | Southern Weed Science Society |
| Location: | Memphis, TN |
| File Formats: | |
| Abstract: | In the turfgrass transition zone, bermudagrass [Cynodon dactylon (L.) Pers.] is often grown in close proximity to cool-season grasses like creeping bentgrass (Agrostis stolonifera L.), Kentucky bluegrass (Poa pratensis L.), and perennial ryegrass (Lolium perenne L.). Inevitably, bermudagrass often becomes an invasive weed in neighboring cool-season grasses. Lack of selective herbicides makes it difficult to suppress (prevent spread without discoloration) or control bermudagrass in infested cool-season grasses. Field studies were conducted in Blacksburg, VA to evaluate several herbicides and plant growth regulators for selective bermudagrass control or suppression in creeping bentgrass, Kentucky bluegrass, and perennial ryegrass. Strips of common bermudagrass ‘Vamont’ sod were established in perennial ryegrass and ‘Kelly’ Kentucky bluegrass. In contrast, creeping bentgrass ‘Penncross’ sod strips were established into plots of ‘Tifway’ hybrid bermudagrass. In all cases, chemical treatments were evaluated for affects on bermudagrass encroachment into the cool-season grass and visual quality of desirable turfgrass. The objectives were to determine methods to selectively control bermudagrass with minimal injury to cool-season grass or to limit bermudagrass encroachment into cool-season grasses without decreasing visual quality of either species. Plots were 2 m by 2 m with a 0.3 m wide by 2 m long strip of sod established in the center. Treatments were initiated May 16, 2003 and applied every three weeks until August 29, 2003 for a total of six treatments. Bermudagrass was green and growing at first treatment. Mowing heights were 1.6, 2.5, and 1.6 cm for creeping bentgrass, Kentucky bluegrass, and perennial ryegrass, respectively. Treatments were applied at 280 L/ha and included the following: ethofumesate at 1.68 kg ai/ha, flurprimidol at 0.84 kg ai/ha, ethofumesate + flurprimidol, siduron at 13.44 kg ai/ha, fenoxaprop at 0.04, 0.06, and 0.08 kg ai/ha, fluazifop at 0.04, 0.07, and 0.1 kg ai/ha, mesotrione at 0.28 kg ai/ha, isoxaflutole at 0.28 kg ai/ha, triclopyr at 1.1 kg ai/ha, fenoxaprop at 0.06 kg/ha + ethofumesate, and fenoxaprop at 0.06 kg/ha + flurprimidol. The entire experimental area was treated with propaconizol at 0.5 kg ai/ha. Mesotrione and isoxaflutole were not included in the creeping bentgrass study. In perennial ryegrass, the two higher rates of fenoxaprop, fenoxaprop + triclopyr, fenoxaprop + ethofumesate, isoxaflutole and all rates of fluazifop controlled bermudagrass greater than 90% 18 weeks after initial treatment (WAIT). The two higher rates of fluazifop caused unacceptable injury to perennial ryegrass. In Kentucky bluegrass, the two higher rates of fenoxaprop, fenoxaprop + triclopyr, all rates of fluazifop, and isoxaflutole controlled bermudagrass greater than 90% at 18 WAIT. Ethofumesate + flurprimidol and the two higher rates of fluazifop caused unacceptable injury to Kentucky bluegrass. In creeping bentgrass, only ethofumesate + flurprimidol selectively controlled bermudagrass 68%. Other treatments either did not control bermudagrass or were too injurious to creeping bentgrass. Siduron did not control bermudagrass, but decreased lateral growth without causing discoloration of bermudagrass or creeping bentgrass. |
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