GFM Network News


The stage of lamb’s quarters when it is most susceptible to conventional herbicides. When lamb’s quarters is taller than 10 cm, control with glyphosate is reduced when applying at a rate of 0.67 l/ac. (540 g/l concentration). Increasing the rate to 1.34 l/ac. is needed to achieve adequate control.

Pest Patrol: Maximizing control of common lamb’s quarters

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 2 minutes Lamb’s quarters has consistently been identified as the most abundant and problematic weed affecting field crop production in Ontario even though the Pest Management Regulatory Agency database contains hundreds of herbicides that list lamb’s quarters as a susceptible weed. There is an arsenal of products available to farmers for the control of this weed, so […] Read more

A check strip on left where the Weed Zapper was not used — visible effects on weeds apparent on the right side.

Pest Patrol: Weed Zapper offers an alternative solution for killing weeds

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 2 minutes One day during the summer of 2019, our future daughter-in-law came home one day pretty pumped about a new piece of farm equipment she had heard about. Shelby’s father’s farm has been in organic crop production for about 20 years now, and “some guy” was coming to try to zap the weeds in the soybeans. […] Read more


Farmers are looking for a solution to glyphosate-resistant Canada fleabane, which is a growing concern.

Can less be more when tackling herbicide resistance?

A coming formulation of glufosinate seeks to cut rates yet maintain efficacy

Reading Time: 4 minutes In the past five years, growers across Canada have been hearing more and more about a new weed control mantra. It’s called “doing only what’s necessary.” Weeds continue to challenge and frustrate in the field, of course, and there are always new issues like resistance in species such as Canada fleabane in the East or […] Read more

Waterhemp is now resistant to seven modes of action and is also showing signs of metabolic-based resistance.

New threat to weed management

Metabolic-based resistance is setting off alarms south of the border. There won’t be any easy answers

Reading Time: 6 minutes Here in the 2020s, herbicide resistance seems just part of the reality of managing weeds. It’s certainly not a new topic. We faced resistance to atrazine in the 1970s, then Group 2 ALS inhibitors in the 1990s and a more recent, widespread resistance to glyphosate. But of course the resistance threat keeps getting more complicated: […] Read more


Pest Patrol: Controlling weeds in non-GMO soybeans

Pest Patrol: Controlling weeds in non-GMO soybeans

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 3 minutes Weed control has always been a concern in non-GMO soybeans. Control of broadleaf weeds like lamb’s quarters and common ragweed has been inconsistent, and growers are always looking for ways to improve their results. General principles for weed control in non-GMO soybeans 1. Budget $80 to $85 per acre for weed control and plan for […] Read more

These thriving kochia plants are probably resistant to more than one herbicide mode of action.

Using a multi-prong strategy against herbicide resistant weeds

There are more pre-seed control options available to suppress herbicide-resistance, but use cultural management as well

Reading Time: 4 minutes More than half of western Canadian fields under annual crop production contain at least one herbicide-resistant biotype, according to surveys from 2014 to 2017. In Alberta, roughly 60 per cent of fields surveyed have resistant weeds; in Saskatchewan that figure is 57 per cent and in Manitoba it’s 68 per cent. “The surveys have been […] Read more


Canada fleabane rosette during October.

Pest Patrol: Management practices that controlled glyphosate-resistant weeds in 2020

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 3 minutes Several Ontario agronomists recently shared their most successful strategies for managing glyphosate-resistant weeds. Four general strategies were identified: 1. Inclusion of winter wheat in the crop rotation By early spring, winter wheat’s dense ground cover does not provide a good environment for annual weeds, like waterhemp, to germinate. There are also many herbicides that are […] Read more

Figure 1: Annual bluegrass.

Pest Patrol: Bluegrass becomes an emerging problem in field crops

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 4 minutes In Ontario, turf-like grassy weeds are being found in more cultivated fields. In herbicide-tolerant corn and soybean, control with glyphosate has been inconsistent. In cereal and forage crops, fast growth of these grasses in the spring makes them too big to be controlled with herbicides. Let’s review what is being found in fields and how […] Read more


Soybean planting showing leaf injury symptoms caused by a “bleaching” herbicide.

Pest Patrol: Crop injury from herbicide residues more common in 2020

#PestPatrol with Mike Cowbrough, OMAFRA

Reading Time: 4 minutes In 2020, a few farmers observed leaf injury in their soybean crops. The injury caused parts of the leaf to turn white, then yellow (see photo at top). This injury is typically caused by “bleaching” herbicides. It was odd, though, because the bleaching herbicide had been applied to the previous year’s corn crop, and it […] Read more

RWOAC chair Eric Johnson wants to work with farmers to find out their ideas for managing resistant wild oats.

A new plan of attack for resistant wild oats

With more wild oats showing resistance to Group 8 herbicides, this action committee is going on the offence

Reading Time: 5 minutes In the 1970s, the Wild Oat Action Committee was formed to encourage farmers to control the pesky weed, especially with herbicides. Now a new version is back, but with an ironic twist — the herbicides aren’t working. A recent Prairie-wide study reveals 69 per cent of tested wild oats proved resistant to some modes of […] Read more