GFM Network News


A field sample of wild oat screened with three chemical families within the Group 1 mode of action by the Tardif lab. Note there is resistance observed when Puma (a “fop”) was applied, moderate resistance when Achieve (a “dim”) was applied and moderate susceptibility when Axial (a “den”) was applied.

Pest Patrol: Herbicide-resistant wild oats in spring cereals

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 4 minutes Q. Are there any solutions to control herbicide resistant wild oats in spring cereals? A. Wild oats have been an undesirable weed in spring cereal crops for many years, and its control has been limited to a handful of herbicides within the same mode of action (specifically, WSSA herbicide Group 1). Until recently, there have […] Read more

Figure 1. The white fluffy growth on Canada fleabane rosettes following several weeks in the cool and wet environment of the vernalization chamber.

Pest Patrol: White mould and Canada fleabane

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 2 minutes I could barely contain my excitement. What was this fluffy white stuff that had taken down large fleabane rosettes? Had I accidentally stumbled upon an effective biocontrol option for glyphosate-resistant Canada fleabane? I wondered, what would it take to reproduce this potent material so we could inoculate plants throughout Ontario? I quickly took a sample […] Read more


What can potato chips teach you about weed control? You might be surprised.

Pest Patrol: Dealing with bias in pest management research trials

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 2 minutes I have biases. Perhaps that’s a surprising statement coming from someone who is supposed to be impartial, but experiences lead to biases. It’s human nature. The bigger question is how does one account for and neutralize those biases when evaluating something such as a weed control program? That’s the topic that I wanted to tackle […] Read more

Figure 1. Canada fleabane leaf injury caused by 28 per cent UAN.

Pest Patrol: Using 28 per cent to manage Canada fleabane

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 3 minutes I’m thankful that farmers and agronomists share their ideas, experiences and questions with me as it relates to killing weeds. During the winter months I’ll test out ideas in the greenhouse to see if they’re worth taking to the field. I’m fortunate that we have some great public-sector researchers (such as Dr. Page, Dr. Sikkema […] Read more


Figure 1. Hairy galinsoga seedling.

Pest Patrol: More and more hairy galinsoga

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 3 minutes Q: I’m seeing more of a weed called hairy galinsoga, and I’m struggling to control it. Any suggestions? A: Historically, we have found this annual plant mainly in horticultural crops throughout the southern portion of the province, but in the last five years, there have been more inquiries on managing hairy galinsoga in field crops. […] Read more

Figure 1: Unsprayed control.

Controlling scentless chamomile with herbicides

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 3 minutes Several herbicide treatments were evaluated in a 2019 on-farm research trial to determine best management options for scentless chamomile, a weed with a reputation for being difficult to control. Although 10 treatments provided greater than 80 per cent visual control of emerged plants, new seedlings continued to emerge several weeks after application, resulting in a […] Read more


Figure 4: Waterhemp in soybean.

Pest Patrol: Dealing with waterhemp and Canada fleabane

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 3 minutes In last month’s #PestPatrol, we discussed options for the control of glyphosate-resistant waterhemp. However, across the province, there appears to be a more immediate threat for the 2020 season from glyphosate-resistant Canada fleabane. This article will focus on management strategies to control both species at the same time. It is true that glyphosate-resistant Canada fleabane […] Read more

Figure 1: Light green waterhemp plants approaching the top of the soybean canopy after two applications of glyphosate that proved ineffective. At this stage, no herbicide will adequately control waterhemp.

Pest Patrol: Plan to manage waterhemp in 2020

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 2 minutes Waterhemp has spread further across Ontario during the 2019 season and can now be found in eight counties (Bruce, Chatham-Kent, Essex, Haldimand, Lambton, Middlesex, Norfolk and Northumberland). A close relative of pigweed, waterhemp is a competitive annual broadleaf weed that has been found resistant in the province to four different herbicide groups (Group 9: Roundup, […] Read more


Contrast in control of Roundup Ready alfalfa with herbicides applied in early fall (foreground) compared to late fall (background).

Pest Patrol: Killing off Roundup Ready alfalfa

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 3 minutes Six tank-mix partners are recommended for the removal of Roundup Ready alfalfa, and since they vary significantly in cost (Table 1 below), 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 […] Read more

Figure 1: Purple deadnettle in a wheat field — October 2018 at a yield-reducing population density of around 500 plants per square metre.

PHOTOS: Pest Patrol: Purple deadnettle and henbit control in winter wheat

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 3 minutes Q: I’m seeing more henbit and/or purple deadnettle in my winter wheat crop. Should it be controlled, and how? A: Henbit and purple deadnettle are often discussed interchangeably because they look similar, are from the same genus (Lamium) and have similar emergence patterns (mainly in the fall, but henbit will also emerge in spring). Both […] Read more