Vol. 54—2000 - NorthEastern Weed Science Society

ETHOFUMESA TE RESISTANT CREEPING BENTGRASS?
T. L. Watschke and1. A. Borger'
ABSTRACT
In November of 1993, a patch of creeping hentgrass growing in a golf course fairway that
hadbeen suhject to a total of twelve applications ofethofumesate at O.5lhs ailA from 1989 to
1993was sampledforidentificationandplantincreasepurposes.Twelve three-quarterinchplugs
wereremovedfromthepatchandwere transferredto a greenhouseandpottedin four-inchpots.
A positive identificationforcreepingbentgrasswasmadeandtheplugs were grownin thepots
untilSeptemberof 1994. At thattime,a portionof thebentgrassin each pot was transferredto a
flatandallowedto increaseas wastheturfthatremainedin thepot. Anotherportionfromeach
pot was planted in the field to assess seed production potential. By March of 1995, the pots had
filled in and a phytotoxicity stody wasconducted using rates of ethofumesate that ranged from
1.5 to 12.51bs ailA from a single application. No phytotoxicity was observed. In April of 1996,
the bentgrass in the flats was harvested by cutting stolons (with threeto four nodes) with a shears
and placing them in water. After all the flats were harvested, the stolons were transferred to the
ValentineResearchCenterwhereaneighthundredsquarefootareawas stolonizedusingthe
harvested material. Later in 1996, the first seed was harvested from plants space planted in 1994.
This seed was used to establish twelve (one for eacb original flat) plots in an area adjacent to the
sprigged plot. In October of 1996, a phytotoxicity experiment was conducted on the sprigged
plots. Ethofumesate was applied in October and twice in November at rates ranging from I to 4
Ibs ailA for each application. Phytotoxicity was rated in the spring of 1997 and none was found.
Also in 1997, more plot area was established using stolons for one area and a blend of the seed
fromall twelve sources(eachpot) fortheotherarea.Researchon this area,whichcontainsplots
of five other creeping bentgrasses (all conunercially available) andlocally produced annual
bluegrass is under the direction of Dr. David Huff, Penn State's turfgrass breeder. Experiments
arecurrentlyunderway to furtherdocumenthedegreeof apparentresistancethatthe selected
creeping hentgrass possesses. In addition, research will be conducted soon to ascertain whether
the observed resistanceltolerance has a genetic basis that could betransferable.
'Professor andResearchAssistant, respectively,Departmentof Agronomy,PennStateUniversity,University
Parle,PA, 16802
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