Six tank-mix partners are recommended for the removal of Roundup Ready Alfalfa and since they vary significantly in cost (Table 1), their effectiveness was evaluated in a trial conducted at the Elora Research Station in 2018-19. Growing degree day accumulation after herbicide application appeared to have the greatest effect on the control of Roundup Ready alfalfa. Presumably because alfalfa has…
Mike Cowbrough March 22, 2019 1650 Comments Off on What’s Working on the Farm? Practical Solutions for Problem Weeds“Do not be cheap. Weed control is an investment into the current and future crops on every field.” That was parting advice from Norfolk and Oxford County farmer Ann Vermeersch at the 2019 FarmSmart Conference in Guelph. In front of 80 farmers and agronomists, I moderated a session with Vermeersch and Steph Kowalski, a Certified Crop Advisor and Lead…
Mike Cowbrough November 20, 2018 1720 Comments Off on Managing Glyphosate Resistant Canada Fleabane with Cover Crops and TillageMy colleague Dr. Clarence Swanton (University of Guelph) used to say that based on research he did in the 1980’s, one should not expect to control weeds with cover crops. Their utility was in preventing soil erosion and improving soil health but not in significantly reducing weed populations. However, Dr. Swanton has had to re-think his long held position on…
The OMAFRA Guide to Weed Control for Field Crops (Publication 75A) is available in the following formats: ENGLISH PRINT VERSION (2019 – SouthWest Ag Conference Edition): A limited number of print copies have been made that include chapter tabs. If you would like a copy, contact mike.cowbrough@ontario.ca directly. ELECTRONIC VERSION (PDF): click to download
The latest best management practices for common ragweed competing in corn, soybean and winter wheat can be found here: Common ragweed control (Source: Problem Weed Guide for Ontario Crops)
Mike Cowbrough August 8, 2017 2538 Comments Off on Crop response to herbicides applied prior to and after emergence.For over 30 years, the Ontario Agriculture Weed’s team has competed in the Collegiate Weed Science Competition organized by the North Eastern Weed Science Society. In preparation for the “herbicide identification” portion of the competition, an area at the Elora Research Station is planted to a number of different crop and weed species and then sprayed with several herbicides. This training…
Volume 1 of the inaugural “Problem Weed Guide for Ontario Crops” includes management strategies for 19 species in corn, soybean and cereal crops that is cited from work conducted by the University of Guelph Department of Plant Agriculture as well as other peer reviewed studies. This 176 page guide features over 175 images and 50 tables that help illustrate the…
Mike Cowbrough December 5, 2016 5645 Comments Off on Has the adoption of genetically engineered (GE) crops resulted in more herbicide resistant weeds in Ontario?The increased acreage of genetically engineered (GE) crops planted in Ontario has not led to an increase in herbicide resistant weeds according to results from the University of Guelph’s testing laboratory. Table 1 summarizes the number of species confirmed as resistant to common herbicides used in Ontario over the past 40 years. There are currently fewer species resistant to glyphosate,…
Mike Cowbrough October 14, 2016 9163 Comments Off on Should 2,4-D be used to control weeds in emerged winter wheat during the fall?Co-written by Joanna Follings, Cereal Specialist Should you use 2,4-D to emerged wheat in the fall to control weeds? The short answer is no. First, the label clearly states under the “Application Timing” section: “Do not apply to seedling winter cereals in the fall.” Second, there are other labelled and less injurious herbicide options that provide equivalent or better control of…
Effective control of common burdock doesn’t happen overnight and is most successful when you can control new seedlings in the spring followed by controlling any larger first year plants in the fall so that they don’t overwinter, flower and disperse new seed the following year . Common burdock (Arctium minus) is a biennial that reproduces only by seed. Following seed germination…
Mike Cowbrough September 23, 2016 4222 Comments Off on Farmers are reducing weed seed return after cereal harvestI was driving down a long country road and noticed that two large fields, where winter wheat was harvested almost eight weeks ago, had a beautiful thick canopy of oats. It wasn’t long until I came across a field that was left fallow, that it became clear why so many farmers had chosen to plant an oat cover crop. There was…
Featuring over 120 species commonly found in and around agricultural fields, the Weed ID Guide for Ontario Crops is now available in the following formats. ePub format (124 MB file for Kindle, iBooks and other e-reader apps): click to download .pdf format (8 mb file): click to download print ready .pdf (141 mb file): click to download Print Copy (printing and…
Many farmers have witnessed the value in applying herbicides in the fall to perennial weeds, especially perennial sow-thistle and dandelion (Figure 1). Often they will see a reduction in their population the next year as well as a delay in their shoot emergence. This allows the planted crop to have a competitive advantage over those perennial weeds. Unfortunately weather conditions…
Mike Cowbrough April 26, 2016 7116 Comments Off on Annual rye-grass and clover sensitivity to soil applied corn herbicidesby: Dr. Darren Robinson (University of Guelph, Ridgetown Campus) and Mike Cowbrough (OMAFRA) There is interest in inter-seeding annual ryegrass and clover into corn (Figure 1). Research studies have been done in the United States and Canada to determine the tolerance of cover crops to various soil applied corn herbicides. This article provides an overview of the results of that…
In Ontario there are 21 different weed species that are resistant to one or more herbicide groups. The table below contains all records of herbicide resistant weed species in Ontario tested and confirmed by the University of Guelph since 1981 (as of November, 2017) Below are distribution maps of weed species that are resistant to different herbicide groups in Ontario…