DEEP TILLAGE AND GLYPHOSATE REDUCED REDVINE (BRUNNICHIA OVATA) AND TRUMPETCREEPER (CAMPSIS RADICANS) POPULATIONS IN GLYPHOSATE-RESISTANT SOYBEAN (GLYCINE MAX)

Authors: Reddy, Krishna

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2005
Publication Date: 5/18/2005
Citation: Reddy, K.N. 2005. Deep tillage and glyphosate reduced redvine (brunnichia ovata) and trumpetcreeper (campsis radicans) populations in glyphosate-resistant soybean (glycine max). Weed Technology 19:713-718.

Interpretive Summary: Redvine and trumpetcreeper are perennial deep-rooted vines found extensively in crop and noncrop lands in the lower Mississippi Delta region. Transgenic soybean resistant to glyphosate provide the flexibility to use this non-selective herbicide to control both weeds within the crop, but glyphosate alone can not provide complete control. Scientist at the Southern Weed Science Research Unit in Stoneville, MS, completed a 4-yr (2000-2003) field study to determine the effectiveness of fall deep tillage and glyphosate applications on redvine and trumpetcreeper populations and soybean yield. Fall deep ('45 cm) tillage reduced redvine density =88% compared with shallow ('15 cm) tillage, but deep tillage did not reduce trumpetcreeper density. Glyphosate applied preplant reduced trumpetcreeper density (25 to 44%), but not redvine compared with no glyphosate. Glyphosate in-crop postemergence applications reduced density of trumpetcreeper but not redvine compared with no herbicide. Soybean yields were higher with deep tillage vs. shallow tillage, glyphosate preplant application vs. no glyphosate, and glyphosate in-crop postemergence applications vs. no herbicide. These results indicate that fall deep tillage could reduce redvine but not trumpetcreeper populations. Glyphosate could reduce trumpetcreeper density but not redvine. Integration of fall deep tillage and glyphosate applications could be an effective strategy to manage combined infestations of these vines in glyphosate-resistant soybean.

Technical Abstract: Field studies were conducted during 2000-2003 at Stoneville, MS, to determine the effectiveness of fall deep tillage and glyphosate applications on redvine and trumpetcreeper populations and soybean yield in glyphosate-resistant soybean. Fall deep ('45 cm) tillage for 1, 2, and 3 years consecutively reduced redvine density by 95, 88, and 97%, respectively, compared with shallow ('15 cm) tillage, but deep tillage did not reduce trumpetcreeper density. Glyphosate applied preplant reduced trumpetcreeper density (25 to 44%), but not redvine density compared with no glyphosate. Glyphosate early postemergence (EPOST) alone (45 to 67%) or followed by (fb) late postemergence (LPOST) (59 to 83%) reduced density of trumpetcreeper but not redvine compared with no herbicide. However, dry biomass of both vines was reduced with glyphosate EPOST or LPOST compared with no herbicide. Soybean yields were higher with deep tillage vs. shallow tillage, glyphosate preplant application vs. no glyphosate, and glyphosate EPOST alone or fb glyphosate LPOST vs. no herbicide. Redvine and trumpetcreeper did not reestablish in 2003, after skipping fall deep tillage for 1-yr following three consecutive years of deep tillage compared with shallow tillage. It is possible to manage redvine infestations with fall deep tillage and trumpetcreeper infestations with glyphosate preplant and postemergence (POST) in-crop applications. Integration of fall deep tillage and glyphosate POST applications could be an effective strategy to manage combined infestations of these vines in glyphosate-resistant soybean.