Missouri: Although it’s tough to look ahead to 2017 while the 2016 harvest is still wrapping up, it’s important to recall some problematic weeds from this past spring. Both marestail (horseweed) and curly dock (sour dock) have put herbicides and tillage equipment to the test, with many fields requiring separate in-field herbicide applications to try and regain control over these species.

Now is the ideal time to control these two tap-root weeds, along with other winter annual weeds that are germinating strong with the recent moisture and above average temperatures, to simplify efforts next spring.

When it comes to perennial plants like curly dock and dandelion, fall applications provide the ideal timing for systemic herbicides like glyphosate and 2,4-D/dicamba to pull down into the taproot as these plants move nutrients and carbohydrates into their roots for winter survival. Oftentimes, growers can attempt to kill these plants in the spring with contact products that kill above-ground plant tissue without actually killing the root; therefore, regrowth occurs.

Since marestail will continue to germinate well into early spring, lack of control of the fall/winter germinated weeds can pose the biggest issues come a wet spring. Eliminating the first flush that’s in a rosette growth stage is advantageous versus battling spring bolting plants.

Although it’s only November – don’t wait until right before frost for more weeds to emerge. It’s been observed time and time again that when rainfall occurs in the fall and fall applications don’t occur, it leads to a more challenging spring for controlling these weeds. A little added residual herbicide could go a long ways from now until winter.

Check out the links below for more specific technical recommendations for fall marestail control in glyphosate-tolerant (GT) and LibertyLink soybeans:

• Herbicide programs for marestail management for GT soybeans in Missouri (excluding the Bootheel) 
• Herbicide programs for marestail management for LibertyLink soybeans in Missouri (excluding the Bootheel) 

Marestail (left) and curly dock (right) at the Columbia, MO, Grow More Experience site – September 30, 2016.

Submitted by Brett Craigmyle and Brian Norton, agronomic service representatives for Syngenta

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All photos are either the property of Syngenta or are used with permission.