Date of Award
Master of Science
Creeping bentgrass (Agrostis stolonifera L.) is a cool-season, perennial grass used predominately on golf course putting greens in temperate regions of the United States. However, due to the aggressive growth habit of bentgrass, it often spreads into surrounding areas of Kentucky bluegrass (Poa pratensis L.), and is considered a weed because it disrupts turfgrass uniformity. Cultural practices provide little control of creeping bentgrass in Kentucky bluegrass because of the similar characteristics shared between species, and reports of herbicides controlling creeping bentgrass without harming Kentucky bluegrass are unavailable. Therefore, the objective of our research was to selectively control creeping bentgrass using herbicides with safety to Kentucky bluegrass. Experiments were designed to evaluate sulfosulfuron and mesotrione, two herbicides thought to have the capability for selective control. Control of creeping bentgrass with sulfosulfuron was dependent on proper application timing and less dependent on application rate. Applications of sulfosulfuron later in the fall were more effective compared with earlier applications, although no treatment provided > 31 % control. Kentucky bluegrass exhibited minor discoloration and appears tolerant of sulfosulfuron at application rates [less than or equal to] 22 g/ha. Late fall applications of sulfosulfuron may be useful in partially removing creeping bentgrass from a heavily contaminated sward of Kentucky bluegrass, but complete removal is questionable unless greater control can be achieved. Successful postemergence control of creeping bentgrass with mesotrione depended on the proper rate, number of applications, and application interval. Two applications of mesotrione, six weeks apart at 280 g/ha each, provided 69% control of creeping bentgrass. However, greater than 93% control of creeping bentgrass was achieved at rates of 140 or 210 g/ha when multiple applications were made two weeks apart. Kentucky bluegrass quality remained similar to untreated controls and the clipping yield and root production was not affected by mesotrione applications. Applications of mesotrione did reduce overall turfgrass quality by creating caps in the canopy where creeping bentgrass died. These data demonstrate the capability of mesotrione to provide effective postemergence control of creeping bentgrass with safety to Kentucky bluegrass. Mesotrione presents turf managers the opportunity for selective removal of creeping bentgrass in swards of Kentucky bluegrass.
Marcus Andre Jones
Jones, Marcus Andre, "Selective removal of creeping bentgrass from Kentucky bluegrass" (2005). Retrospective Theses and Dissertations. 19124.