TITLE:
Efficacy of 2,4-D Choline/Glyphosate Dimethylamine on Glyphosate Resistant Canada Fleabane (Conyza canadensis) at Different Sizes
AUTHORS:
Laura Ford, Nader Soltani, Darren E. Robinson, Robert E. Nurse, Allan McFadden, Peter H. Sikkema
KEYWORDS:
Glyphosate Resistance, Multiple Herbicide-Resistant Crops, Preplant Herbicides, Postemergence Herbicides
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.5 No.18,
August
26,
2014
ABSTRACT: Glyphosate resistant (GR) Canada fleabane has spread
quickly across southwestern Ontario and new strategies for the control of this
competitive weed must be developed especially in no-tillage crops. A premix of
2,4-D choline and glyphosate dimethylamine (DMA) has been developed for application
on tolerant corn, soybean and cotton crops that provides an option for the
control of this problematic GR weed. The objective of this research was to
determine the required dose needed to effectively control GR Canada fleabane at
different size categories in field and greenhouse experiments. In the field
experiments, nine rates of 2,4-D choline/glyphosate DMA (53.8 to 13,760 g·ae·ha-1)
were applied to GR Canada fleabane that were 10 cm in diameter/tall, 20 cm tall
or 30 cm tall. Similarly, in the greenhouse, seven rates of 2,4-D
choline/glyphosate DMA (0 to 3440 g·ae·ha-1) were applied to 10, 20 and 30 cm tall GR
Canada fleabane plants. The three different size classes of GR Canada fleabane
responded similarly to 2,4-D choline/glyphosate DMA in the field experiment. In
the greenhouse there were some differences in control for the three size classes
of GR Canada fleabane with 2,4-D choline/glyphosate DMA; the 20 and 30 cm tall
plants required similar rates to provide equivalent control, but the 10 cm
plants required a lower rate. In all situations, greater than 1720 g·ae·ha-1 of 2,4-D choline/glyphosate DMA was required to provide 95% control of 10, 20
and 30 cm tall Canada fleabane in greenhouse (35 DAA) and field experiments (8
WAA), respectively.