Response of Honeyvine Milkweed (Ampelamus albidus) to Herbicide Applications

Abstract

Greenhouse studies revealed that glyphosate [N-(phosphonomethyl)glycine] at 3.4 kg/ha or picloram (4-amino-3,5,6-trichloropicolinic acid) at 0.3 kg/ha more effectively reduced further growth of honeyvine milkweed [Ampelamus albidus(Nutt.) Britt.] when treated at a height of 30 cm than did 2,4-D [(2,4-dichlorophenoxy)acetic acid] at 1.1 kg/ha or dicamba (3,6-dichloro-o-anisic acid) at 0.6 kg/ha. Glyphosate or picloram applications were also more effective than 2,4-D or dicamba applications in reducing amount of regrowth that occurred after treated plants were cut at the soil surface. Glyphosate plus 2,4-D, glyphosate plus dicamba, glyphosate plus picloram or 2,4-D plus picloram combinations also effectively reduced further growth of treated plants and subsequent regrowth after plants were initially harvested. Greenhouse studies revealed that glyphosate plus ethephon [(2-chloroethyl)phosphonic acid] at 1.7 plus 0.6 kg/ha or glyphosate plus ammonium sulfate at 1.1 plus 6.7 kg/ha were no more effective than glyphosate alone at 1.7 kg/ha. Dowco 290 (3,6-dichloropicolinic acid) at up to 2.2 kg/ha did not effectively inhibit growth of honeyvine milkweed.