"Weird Weeds" Questions and Answers

Below is a summary of commonly asked questions from the past week relating to herbicide control options for obscure and/or problematic weeds.

Q: What herbicides will control Black medic in corn and soybeans

A: In corn, research trials conducted by Dr. Swanton and Dr. Tardif (University of Guelph) have shown that PeakPlus, Battalion, Marksman (high rate), Summit, Distinct, Ultim Total and Option + Distinct have all provided excellent control of Black medic. Unfortunately in soybeans, the post-emergent herbicides have not offered any satisfactory level of control. A pre-plant burndown of glyphosate at 1-2 L/ac has provided the best level of control.

Q: What controls Downy brome in corn?

A: Not much, we have done very limited work in Ontario. Ultim has offered suppression (70% visual control) of downy brome and has performed better than Option (50% visual control). Based on field observations, glyphosate (RR corn only) or Liberty (LL corn only) would be your best management options.

Q: What will control Henbit in wheat?

A: Field observation in Ontario have suggested that Refine Extra offers control of henbit, while MCPA, 2,4-D, and bromoxynil/MCPA are generally ineffective. Research conducted by the University of Kentucky's Department of Agronomy has also shown that Refine Extra will control henbit.

Q: What will control Corn speedwell in cereals?

A: Research conducted by Dr. Sikkema (University of Guelph) has demonstrated that MCPA, Refine Extra, and dichlorprop/2,4-D offer excellent control of corn speedwell.

More in depth information on most of the above weed species can be found by going to www.ontario.ca/crops and clicking on the "weeds" link and then the "problem weeds in field crops" link.

Related Links

• OMAFRA Website-Crops

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