Vol. 54—2000 - NorthEastern Weed Science Society

lRUMPETCREEPER, HONEYVINEMILKWEED,AND HEMP DOGBANE CONTROL
wrrn POSTEMERGENCECORN HERBICIDES
K. W. Bradley, P. Davis, S. R. King, and E. S. Hagood I
ABSTRACT
Three field experiments were conducted during 1999 in Virginia in separate locations with
severe infestations of trumpetcreeper(Campsis radicans (L.) Seem ex Bureau). honeyvine
milkweed (Ampelamus albidus (Nutt.) Britt.), and hemp dogbane (Apocynum cannabinum L.).
Trumpetcreeperand honeyvine milkweed experimentswere establishedin existing no-tillage
com fields while the hemp dogbane experimentwas established in a fallow area previously
planted in wheat (Triticum aesttvum L.). The sulfonylurea herbicides helosulfuron,
primisulfuron, and prosulfuron plus primisulfuron (Exceed®) were evaluated in all three
experiments, either alone or in combinationwith dicamha at 0.25 or 0.375 lb ai per acre.
Nicosulfuronwas also includedin thehempdogbaneexperiment,eitheralone at 0.031 lb ai per
acre or in combination with 0.5 Ib 2,4-D, or 0.25 or 0.375 Ib dicamba per acre. Glyphosate was
evaluatedin all experimentsat I, 2, and 4 lbs ai per acre as a potentialperennialweed control
tool in glyphosate-tolerant (Roundup Ready"') com. The experimental herbicide ZAI296 was
also evaluated as a postemergencetreatmentin all threeexperiments. ZA1296 was applied.
either alone at 0.941b ai per acre or in combination with 0.25 or 0.375 lb dicamba per acre, 0.5 lb
2,4-D per acre, 0.0178 lb primisulfuron per acre, 0.012 lb rimsulfuron per acre, or 0.012 lb
rimsulfuron plus 0.5 Ib 2,4-D per acre.
ZAI296 in combination with either 2,4-D, dicamba, or rimsulfuron plus 2,4-D provided
greaterthan70% controlof tnnnpetcreeperat 3 monthsaftertreatment(MA1'). Similarlevels of
trumpetcreeper control were achieved with the 4.0 lb glyphosate rate, while slightly lower levels
of control were observed when dicamba was added to the halosulfuronor prosulfuronplus
primisulfuron treatments. Halosulfuron, primisulfuron, and prosulfuron plus primisulfuron
providedessentiallyno trumpetcreepercontrolwithouttheadditionof dicamba.
At 3MA T, ZAI296 in combination with rimsulfuron and 2,4-D provided 75% control of
honeyvine milkweed. When applied in combination with dicamba, halosulfuron, primisulfuron,
and ZAI296 provided levels of honeyvine milkweed control ranging from 53 to 68%.
Honeyvine milkweed control was less than 50% when halosulfuron, primisulfuron and
prosulfuronplusprimisulfuronwereappliedalone,andalso withall ratesof glyphosateapplied.
When applied in combination with dicamba, ZA1296 provided 89 to 94% control of hemp
dogbane at 3MAT. Slightly lower levels of control were achieved with nicosulfuron in
combinationwith either2,4·D or dicamba. Whenappliedalone, both nicosulfuronand ZA1296
providedessentially no hemp dogbanecontrol. The combinationof halosulfuron, primisulfuron,
or prosulfuronplus primisulfuronwith either rate of dicambaprovided 76 to 88% control of
hemp dogbane. However, the level of controlachieved by the additionof these sulfonylureas
was usuallynot statisticallydifferentfromthe controlaffordedby eitherrateof dicambaalone.
10rad. Res. Asst., Ext. Agent., Grad. Res. Asst, and Prof., Dept. of Plant Path., Phys., and Weed
Science, Virginia Polytechnic Institute and State Univ., Blacksburg, VA 24061
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