Vol. 54â2000 - NorthEastern Weed Science Society
Vol. 54â2000 - NorthEastern Weed Science Society
Vol. 54â2000 - NorthEastern Weed Science Society
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ANNUAL BLUEGRASS (PDaannual CONTROL WITH ETHOFUMESA TE<br />
S.E. Hart and D.W. Lycan'<br />
ABSTRACT<br />
Field Experimentswereconductedin 1999attheRutgersUniversity<br />
Experimental Horticultura1 Farm II in New Brunswick NJ and the Little Mill Country<br />
Club in Marlton NJ to evaluate spring and summer applications of ethofumesate for<br />
control of annual bluegrass in bentgrass fairways maintained at a mowing height of 9<br />
mm. At Horticultura1 Farm II the turfwas colonial bentgrass (Agrostis tenuis) variety 'SR<br />
7100' infested with approximately 40% P. annua while the turfat Little Mill was a<br />
mixtureof unknownvarietiesof creepingbentgrass(Agrostispalustris)andperennial<br />
ryegrass (Lolium perenne} infested with approximately 60% P. annua. Ethofumesate<br />
applicationswere initiatedon AprilS andapplied8 timesatapproximately3-week<br />
intervals throughout the spring and summer. Ethofumesate was applied four times at 1.7,<br />
1.1 or 0.8 kg aiJh followed by four applications at 0.8,0.6 or 0.4 kgIh, respectively. All<br />
ethofumesate applications were applied with 4.8 kg!h ofurea and 9.1 kg/h iron chelate.<br />
One application ofpaclobutrazol at 0.6 kg!h applied late April was also evaluated for<br />
controlof P. annua.All herbicideapplicationswereappliedwitha C02 backpacksprayer<br />
delivering 740 Liha.<br />
Ethofumesate applied twice at 1.7, 1.1, or 0.8 kg/h provided 59, 62-82 and 80<br />
83% P. annua seedhead suppressionas comparedto untreatedplots on May zo".Priorto<br />
theonsetof high summertemperatures. threeapplicationsof ethofumesatcat 1.7. 1.1,or<br />
0.8 kg/h reduced P. annua populations at Horticultura1 farm II from 38 to 22, 16 and<br />
20%, respectively. However, injuryto bentgrass was 25, 15, and 5%, respectively.<br />
Paclobutrazol reduced P. annua populations to 26% with no bentgrass injury. At Little<br />
Mill threeapplications ofethofumesate at 1.7, 1.1, or 0.8 kglh reduced P. annua<br />
populationsfrom62 to 16,23 and32%,respectively.However,injuryto bentgrasswas<br />
55,53, and 33%, respectively. Paclobutrazol reduced P. annua populations to 34% with<br />
no bentgrass injury. Throughout the summer P. annua populations declined in the<br />
untreatedplots due to summerheatstressbutappreciableincreasesin P. annuacontrol<br />
were not detected with additional applications of ethofumesate while bentgrass turf<br />
quality continued to be lower as compared with untreated or paclobutrazol treated<br />
bentgrass. In September, following all eight applications of ethofumesate, P. annua<br />
populationswereonly significantlylowerthenuntreatedplotsat LittleMill when<br />
ethofumesatewas appliedatthehighestapplicationrates.<br />
Theresultsof thesestudiessuggestthatspringapplicationsof ethofumesatemay<br />
potentiallyprovideseedheadsuppressionandsubstantialpopulationreductionsof P.<br />
annua.However.summerapplicationof ethofumesatecouldnot furtherreduceP. annua<br />
populationsandcontinuedto causeunacceptableinjuryto bentgrass.Thevigorreduction<br />
of bentgrassmay haveallowedP. annuato moreeasily reinfesttheethofumesatetreated<br />
plots in late summer.<br />
1 Asst Prof.andProgramAssoc., New JerseyAgriculturalExperimentStation,CookCollege, Rutgers,The<br />
StateUniversityof New Jersey.New BrunswickNJ 08901<br />
99
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