Proceedings of the Sixty-first Annual Meeting of the Northeastern ...

128
APPLICATIONS FOR SULFENTRAZONE USE ON GOLF TURFS. S.J. McDonald,
Turfgrass Disease Solutions, Pottstown, PA and P.H. Dernoeden, Univ. of Maryland,
College Park.
ABSTRACT
Sulfentrazone was labeled for use on turfgrasses in 2006 and is sold under the
trade name of Dismiss ® . According to the label, creeping bentgrass (Agrostis
stolonifera), red fescue (Festuca rubra), tall fescue (Festuca arundinacea), perennial
ryegrass (Lolium perenne), Kentucky bluegrass (Poa pratensis), bermudagrass
(Cynodon dactylon) and zoysiagrass (Zoysia japonica) are tolerant of sulfentrazone.
The label, however, does not specify different rates based on turfgrass species. The
herbicide’s primary use in turf is for postemergence control of yellow and purple
nutsedge (Cyperus spp.), and green and false green Kyllinga (Kyllinga spp.).
Numerous broadleaf weed species are listed as being controlled or suppressed. To our
knowledge, this herbicide has not been formally evaluated for use on turfgrasses in the
Philadelphia to Washington D.C. corridor. Initial studies in College Park, MD, showed
that sulfentrazone (0.375 lb ai/A) applied in May 2006 was highly effective in controlling
yellow nutsedge (C. esculentus) in perennial ryegrass maintained to a height of 2.5
inches. On creeping bentgrass golf course fairways maintained to a height of 0.5
inches in Lothian, MD a single application of sulfentrazone in July killed exposed leaves,
but the yellow nutsedge recovered either from stems or tubers. The aforementioned
observation suggests that under low mowing insufficient leaf area is exposed, which
may result in less herbicide uptake and therefore inadequate translocation of active
ingredient to stems and tubers. Sulfentrazone (0.125, 0.250, and 0.375 lb ai/A) was
applied once in August 2006 to “Crenshaw’ creeping bentgrass and Tufcote
bermudagrass maintained at 0.5 inches in College Park and no injury was observed.
The same rates applied to ‘Zenith’ zoysiagrass maintained at 0.5 inches elicited an
objectionable level of injury for about two weeks, especially the high rate. Sulfentrazone
(0.125, 0.250, and 0.375 lb ai/A) was applied either once or twice to a golf course
fairway in Pottstown, PA beginning on 17 August and sequential treatments were
applied 31 August 2006. The fairway consisted of approximately 45% creeping
bentgrass, 30% perennial ryegrass, 5% annual bluegrass (Poa annua) and 20%
goosegrass (Eleusine indica). The 6 to 8 tiller, seedhead bearing goosegrass was
severely injured, but even at the highest rate (0.375 + 0.375 lb ai/A) only 42% control
was achieved. Sulfentrazone elicited unacceptable injury to the perennial ryegrass
following the sequential application at the highest two rates. Injury to creeping
bentgrass was slightly objectionable following the sequential application of the high rate.
While the level of goosegrass control was poor, data and observations suggest that an
earlier sulfentrazone application to less mature goosegrass may be effective. More
research also is needed to elucidate the impact of mowing height and application timing
on sulfentrazone performance and the influence of air temperature on the sensitivity of
mid-Atlantic turfgrasses to this herbicide.
110