Trumpetcreeper response to selected herbicides

Field studies were conducted to; (1) attempt trumpetcreeper [Campsis radicans (L.) Seem.] control with preemergence and foliar postemergence herbicides labelled for use in no-till soybeans [Glycine max (L.) Merr.], (2) determine the effect of repeated paraquat (1,1'-dimethyl-4,4'-bipyridinium ion) applications and, (3) attempt trumpetcreeper control in non-cropped areas.

Trumpetcreeper was not controlled by preemergence herbicides labelled for use in soybeans. Foliar postemergence herbicides were applied when trumpetcreeper shoots were approximately 1 meter long. Glyphosate [N-(phosphonomethyl)glycine] gave the most complete control of trumpetcreeper of the postemergence herbicides labelled for use in soybeans. Acifluorfen [5-(2-chloro-4-(trifluoromethyl)phenoxy)-2- nitrobenzoic acid], and dinoseb (2-sec-butyl-4,6-dinitrophenol) alone or in combination with naptalam ([N-1-naphthylphthalamic acid) or alachlor [2-chloro-2' ,6'-diethyl-N-(methoxymethyl)acetanilide], gave initial trumpetcreeper control, but regrowth occurred quickly.

Repeated paraquat applications did not control trumpetcreeper. Regrowth occurred when paraquat was applied at 4 or 2 week intervals; however, total shoot necrosis was observed after the third treatment, regardless of the application interval. Applications at 2 week intervals prevented the formation of leaves. Repeated paraquat applications did not appear to reduce trumpet creeper stands the season following applications.

Several herbicides were evaluated for trumpetcreeper control in non-cropped areas. Dicamba (3,6-dichloro-o-anisic acid), 2,4-D [(2,4-dichlorophenoxy)acetic acid], glyphosate, SC-0224 (chemistry not released), 2,4,5-T[(2,4,5-trichlorophenoxy)acetic acid], and XRM-4660 (chemistry not released) gave near complete control during the season of application. Dicamba, fosamine [ethyl hydrogen (aminocarbonyl)phosphonate],glyphosate, and SC-0224 gave near complete control the season following applications with no regrowth.