GFM Network News


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

The trouble with identifying waterhemp in the field is that growers often dismiss it as one of the other pigweed species.

The latest on waterhemp

Incredibly, the weed is already resistant to four modes of action in Ontario, with more in danger

Reading Time: 6 minutes In U.S. farm media circles, it seems that every week there’s another report, another bulletin, another research paper about waterhemp. Often it’s a confirmation of another find in a midwest county or state. More recently, reports indicate the weed is resistant to seven different modes of action with the latest — Group 15 herbicides — […] 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

Although it has yet to be confirmed in Ontario, Palmer amaranth is capable of rapid spread and should be treated as glyphosate resistant.

Recognize the threat of these invasive weeds

How big a problem can waterhemp and Palmer amaranth really be? Let’s not find out

Reading Time: 7 minutes Has everyone been crying wolf about waterhemp? After all, haven’t we been hearing warnings in southern Ontario about the weed for the past 15 years, and who has lost a bushel? Well, it was actually 17 years ago — 2002 — when the species was first confirmed in Lambton County, and the good news is […] Read more


Each waterhemp plant can produce one million seeds, with some producing up to five million.

Waterhemp knocking at Canada’s door

This cousin of the feared Palmer amaranth has reached the Canadian border, and could soon begin marching across the West

Reading Time: 4 minutes A new alien is lurking in the fields of North Dakota and Minnesota, preparing to invade Canada and cause no end of trouble. The potential enemy is a noxious weed called waterhemp, a member of the pigweed family and a cousin of Palmer amaranth, a glyphosate-resistant weed currently plaguing cotton and soybean growers in the […] Read more