Volunteer rapeseed infestation and management in corn

Abstract

The study was conducted to evaluate the effect of different termination timings for rapeseed (Brassica napus L.) cover crop on biomass production, termination efficiency, and volunteer infestation in the successive cash crop (corn, Zea mays), and control of volunteer rapeseed with herbicides. Delaying termination from 28 days before planting corn (DBP) to 14, 5, or 1 DBP, increased rapeseed biomass by 85%, 148%, and 158%, respectively. Rapeseed termination efficiency was greatest 28 DBP (99%) followed by 14 DBP (92%) and 5 DBP (89%) with the combined use of a roller-crimper and 2,4-D [2,4-dichlorophenoxy acetic acid] + glufosinate [2-amino-4-(hydroxymethylphosphinyl) butanoic acid]. The sole use of roller-crimper 1 DBP provided only 56% termination efficiency. Zero volunteer plants were observed in successive cash crops with the 28 DBP termination treatment; however, at 14, 5, and 1 DBP termination, the number of volunteer rapeseed plants m−2 were 5, 12, and 22, respectively. Regression analysis showed that variation in volunteer rapeseed density can be explained better by termination efficiency (R2 = 0.80) as compared to rapeseed biomass at termination (R2 = 0.46). Among pre-emergence (PRE) herbicides, mesotrione [2-(4-mesyl-2-nitrobenzoyl)-3-hydroxycylohex-2-enone], rimsulfuron [N-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]-3-(ethylsulfonyl)-2-pyridinesulfonamide], and flumioxazin {2-[7-fluoro-3,4-dihydro-3-oxo-4-(2-propynyl)-2H-1,4-benzoxazin-6-yl]-4,5,6,7-tetrahydro-1H-isoindole-1,3(2H)-dione} provided more than 95% volunteer rapeseed control, and 92%–94% control with PRE-application of atrazine [6-chloro-N-ethyl-N9-(1-methylethyl)-1,3,5-triazine-2,4-diamine], isoxaflutole [(5-cyclopropyl-4-isoxazolyl)[2-(methylsulfonyl)-4-(trifluoromethyl)-phenyl]methanone], metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one], and pyroxasulfone [3-[[[5-(difluoromethoxy)-1-methyl-3-(trifluoromethyl)-1H-pyrazol-4-yl]methyl]sulfonyl]-4,5-dihydro-5,5-dimethylisoxazole]. Among post-emergence (POST) herbicides, atrazine and glyphosate [N-(phosphonomethyl) glycine] provided 99% control of rapeseed followed by glufosinate (89%). Results indicate that ineffective or delayed termination of rapeseed can result in volunteer infestation in successive crops, which can be controlled by tested PRE and POST herbicides at an early stage.