GFM Network News


Drought stress symptoms in corn leaves where no soil-applied herbicides had been applied and weed control was done with a late post-emergence application.

Pest Patrol: Don’t be cheap with weed control

#PestPatrol with Mike Cowbrough, OMAFRA

“Weed control is an investment into the current and future crops on every field.” The above quote 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 […] Read more

Some plants along the rail line are glyphosate resistant.

Pest Patrol: Sanitation of weed seed

#PestPatrol with Mike Cowbrough, OMAFRA

Q: Can we stop the spread of weed seeds? A: “I’ve been thinking a lot about sterility lately.” I knew as soon as the words came out of my mouth that I had slipped up. I was responding to a question in the audience at a local crop conference about ways to stop the movement […] Read more


Figure 4: A close up of foliar leaf burn from ATS and herbicide applications in 2018.

Pest Patrol: Questions about sulphur deficiency

#PestPatrol with Mike Cowbrough, OMAFRA

I’m asked if growers can mix ammonium thiosulphate (ATS) with herbicides and fungicides to address sulphur deficiency symptoms, or should they apply it separately with streamer nozzles? With reductions in atmospheric sulphur deposits, Ontario research has found significant sulphur responses (10-14 bu./ac.) on some fields, while others have shown little or no response, especially where […] Read more

A seedling adzuki bean plant.

Pest Patrol: Managing volunteer adzuki beans

#PestPatrol with Mike Cowbrough, OMAFRA

Q: Has any work been done with controlling adzuki beans in IP, non-GMO soybeans? A: Chris Kramer and colleagues at the University of Guelph evaluated management of volunteer adzuki beans (photo at top) during a period of four seasons. The main challenge with adzuki beans is that their pods shatter easily and their seed coat […] Read more


Figure 1: This unsprayed control treatment consists mainly of common ragweed but with green foxtail, common lamb’s-quarters, witchgrass, crabgrass and red-root and green pigweed.

Pest Patrol: Weed control in identity-preserved, non-GMO soybeans

#PestPatrol with Mike Cowbrough, OMAFRA

A decade of public research trials evaluating weed control in non-GMO soybeans at the University of Guelph has demonstrated that the key to success is to start with a soil-applied herbicide program that has three or more different modes of action. In Ontario, there are a number of common weeds (e.g. common ragweed, lamb’s-quarters, foxtail […] Read more



Figure 1. An overhead look at the level of control that cereal rye has provided when it was seeded the previous fall (mid- November) at 60 lbs./ac. (left) compared to no cereal rye planted (right).

PHOTOS: Pest Patrol: Cover crops versus glyphosate-resistant weeds

#PestPatrol with Mike Cowbrough, OMAFRA

Q: Can cover crops be an effective tool to manage glyphosate-resistant weeds? A: My colleague Dr. Clarence Swanton (University of Guelph) used to say that based on research he did in the 1980s, one should not expect to control weeds with cover crops. Their utility was in preventing soil erosion and improving soil health but […] Read more

An infestation along an old rail line and a field border.

PHOTOS: Pest Patrol: Reining in dog strangling vine

#PestPatrol with Mike Cowbrough, OMAFRA

Q: I’m seeing a weed called dog strangling vine along roadsides, in woodlots and creeping into agricultural fields. It seems quite invasive. How do I get rid of it? A: Your suspicions are correct. Dog strangling vine is invasive and is listed as a noxious weed under the Ontario Weed Control Act, and regulated as […] Read more


Figure 1. A robotic weeder being tested as part of an engineering design project at the University of Guelph.

Pest Patrol: New herbicide names may not mean new chemistry

#PestPatrol with Mike Cowbrough, OMAFRA

Q: Do I have new opportunities in weed control in 2018? A: This is the question I’ve been asked a lot this past winter meeting season, and one I always struggle to answer. There are some legitimately promising concepts being tested such as robotic weeders (Figure 1 at top) and weed seed destruction tools, but […] Read more

Hemp dogbane in Roundup Ready soybean prior to the spot application of glyphosate.

PHOTOS: Pest Patrol: Dealing with hemp dogbane

#PestPatrol with Mike Cowbrough, OMAFRA

Q: I’ve been battling hemp dogbane in my soybean fields. It produces a milky juice that can stain my beans. What can I do to knock back the top growth so it won’t affect crop quality? A: It’s good that your expectations are for top growth control of hemp dogbane (see figure 1), since it’s […] Read more