Numerous studies have shown that leaving weeds
unaddressed for an extended period results in a loss of valuable resources such
as moisture and residual fertility (namely nitrogen). I think we can all agree
that this year we definitely need to manage our resources as well as possible in
order to rebound from 2011. Taking out these weeds as early as possible is an
essential part of this process. Many producers in Oklahoma have adopted limited
or no-till production techniques. Due to the lack of tillage in these systems,
producers often experience an increase in winter and spring annual weed problems
including horseweed, Russian thistle and kochia. Consequently, preplant burndown
herbicides are essential to replace tillage as the primary weed management tool
in these systems. Two of the most troublesome winter/spring weeds present in
limited tillage or no-till cotton fields are Russian thistle and horseweed.
Weed management research conducted by Dr. Wayne Keeling in the High Plains has focused on the evaluation of different products for the control of Russian thistle. In his research, paraquat has shown excellent activity on Russian thistle, but has not been effective on horseweed. In Oklahoma, glyphosate applied alone has proven very inconsistent at best when trying to control horseweed. In addition, the recent confirmation of glyphosate resistant horseweed in Oklahoma magnifies the importance of additional chemistries. Studies conducted in Oklahoma have shown that effective control of horseweed can be achieved by including dicamba (Banvel, Clarity, etc.) or 2,4-D with glyphosate. However there are some caveats that go along with their use. First, weed size at application time is critical for success. Excellent control of horseweed has been observed when applications have been made to horseweed in the rosette stage (flat or prostrate, prior to bolting or vertical growth). Secondly, it is important to take note of the plant back restrictions required for both dicamba and 2,4-D. When using dicamba, planting may occur 21 days after an application as long as 1 inch of rainfall has been received within that period. In addition Dicamba is not recommended for use in areas that receive less than 25 inches of annual rainfall. For 2,4-D, studies have shown that planting may occur 30 days after application without concerns of crop injury or yield reduction. The following flyer is a reminder we often distribute at meetings to remind growers of both the need and our best recommendations for preplant horseweed control in the spring
Weed management research conducted by Dr. Wayne Keeling in the High Plains has focused on the evaluation of different products for the control of Russian thistle. In his research, paraquat has shown excellent activity on Russian thistle, but has not been effective on horseweed. In Oklahoma, glyphosate applied alone has proven very inconsistent at best when trying to control horseweed. In addition, the recent confirmation of glyphosate resistant horseweed in Oklahoma magnifies the importance of additional chemistries. Studies conducted in Oklahoma have shown that effective control of horseweed can be achieved by including dicamba (Banvel, Clarity, etc.) or 2,4-D with glyphosate. However there are some caveats that go along with their use. First, weed size at application time is critical for success. Excellent control of horseweed has been observed when applications have been made to horseweed in the rosette stage (flat or prostrate, prior to bolting or vertical growth). Secondly, it is important to take note of the plant back restrictions required for both dicamba and 2,4-D. When using dicamba, planting may occur 21 days after an application as long as 1 inch of rainfall has been received within that period. In addition Dicamba is not recommended for use in areas that receive less than 25 inches of annual rainfall. For 2,4-D, studies have shown that planting may occur 30 days after application without concerns of crop injury or yield reduction. The following flyer is a reminder we often distribute at meetings to remind growers of both the need and our best recommendations for preplant horseweed control in the spring
Yangzhou pioneer chemical CO.,LTD |
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