TADS 14776, Manor, Kerb and Corsair Herbicides for Use as Spring Transition Aids in Overseeded Common Bermudagrass Turf

Abstract

Spring transition of overseeded turf has become a major challenge to turfgrass managers in the southern United States. Turf-type ryegrasses which exhibit increased mowing and heat tolerance have made the return of bermudagrass problematic, especially in common bermudagrass. Herbicides were evaluated for use as a Spring transition agent to decrease ryegrass competition/enhance bermudagrass. Treatments of TADS 14776 experimental herbicide, Manor, Kerb and Corsair were applied to overseeded common bermudagrass on may 6, 2001. Application of TADS experimental herbicide at all rates above 0.21 ounce/product increased bermuda enhancement over Kerb, Corsair and Manor, by 29 June 2001. When applied with extra fertilizer applications, the 0.21 ounce rate of TADS was greater than that of Kerb, Corsair and Manor for bermuda transition. TADS applied at the highest rate of 0.64 ounce (+) fertilizer, and TADS @ 0.42 ounce (+) GENAPOL 150 surfactant and extra plot fertilizer, were the first treatments to exhibit total necrosis of the perennial ryegrass overseed by 4 June (1 month after treatment). However, these treatments created a poorer quality turf, compared to other treatments. TADS @ 0.42 ounce (+) extra plot fertilizer ranked highest in bermudagrass plot cover, with five times as much bermudagrass present than untreated controls on 29 May. This same treatment continued with this trend, achieving 100% bermudagrass cover by 29 June (highly desirable). This treatment resulted in a brief decrease in turfgrass quality at 9 and 16 days after treatment (14 May, 21 May). With that in mind, TADS @ 0.42 ounce (+) extra plot nitrogen proved to be the best treatment that produced acceptable levels of turf quality throughout the transition, yielding the fastest re-establishment of the underlying common bermudagrass. At the close of the test on 10 July, TADS @ 0.21 ounce (+) fertilizer and TADS @ 0.42 ounce (+) fertilizer closed with 88% and 99% bermudagrass cover, and mean quality scores of 6.0 and 7.0 respectively. At the close of the test, untreated overseeded common bermudagrass yielded unacceptable turf quality, 19% bermudagrass cover, 14% living green ryegrass cover, with the remainder being dead ryegrass (straw).