Three field studies were conducted during 1998 to 2002 at Stoneville, MS, to examine the efficacy of glufosinate and glyphosate on redvine and trumpetcreeper control in glufosinate- and glyphosate-resistant soybean. Glyphosate at 2.52 kg ae/ha applied approximately 3 wk before planting soybean reduced trumpetcreeper density (45 to 52%) but not redvine compared with no glyphosate in both glufosinate- and glyphosate-resistant soybean. However, glyphosate applied preplant reduced biomass of both species in glufosinate-resistant soybean. Glyphosate early postemergence (EPOST) followed by (fb) late postemergence (LPOST) had no effect on redvine density but reduced trumpetcreeper density (70%) compared with the no-herbicide control. There were no differences in densities and biomass of redvine and trumpetcreeper and soybean yield among isopropylamine, diammonium, and aminomethanamide dihydrogen tetraoxosulfate salts of glyphosate. Overall, trumpetcreeper is more susceptible to glyphosate than redvine. Glufosinate EPOST with or without acifluorfen or glufosinate EPOST fb LPOST had no effect on densities of redvine and trumpetcreeper but reduced biomass 45 to 76% and 35 to 58%, respectively, compared with the nontreated control. These results show that glyphosate preplant and POST in-crop applications can reduce trumpetcreeper density but not redvine, and glufosinate POST applications can suppress growth of both species.
Nomenclature: Acifluorfen; clomazone; glufosinate; glyphosate; lactofen; redvine, Brunnichia ovata (Walt.) Shinners #3 BRVCI; soybean, Glycine max (L.) Merr. ‘DP4690 RR’, ‘DP 5806 RR’, ‘AG 4702 RR’, ‘A 5547 LL’; trumpetcreeper, Campsis radicans (L.) Seem. ex Bureau # CMIRA.
Additional index words: Glyphosate formulation, perennial vine, transgenic soybean, weed biomass, weed density.
Abbreviations: Adt, aminomethanamide dihydrogen tetraoxosulfate; Dia, diammonium; EPOST, early postemergence; fb, followed by; Ipa, isopropylamine; LPOST, late postemergence; POST, postemergence; PRE, preemergence; WAP, weeks after planting soybean; WAT, weeks after late postemergence.
