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Waterhemp peeks out among soybeans.
Crops

Waterhemp on the rise

Manitoba’s list of affected municipalities keeps growing

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Reading Time: 3 minutes Glacier FarmMedia – Manitoba’s ag sector is trying to hold the line against big yield-killing threats like waterhemp and Palmer amaranth. Unfortunately, the number of municipalities where waterhemp has been found just grew by two. “Waterhemp and Palmer amaranth are Tier 1 weeds regulated under the Noxious Weeds Act. They must be destroyed when they’re found,” said Manitoba Agriculture weed extension specialist […] Read more
For IP and Roundup Ready soybeans, the message on Canada fleabane is simple: control it early.
Crops

The one-two weed punch farmers are up against

Managing Canada fleabane and waterhemp is an ongoing challenge for IP and Roundup Ready soybean growers

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Reading Time: 4 minutes The invasion continues. From 2010 to 2015, glyphosate-resistant Canada fleabane spread from Windsor to the Quebec border — more than 800 kilometres in just six years. Along the way, it evolved resistance to Groups 2 and 9 modes of action. Waterhemp has also spread rapidly, with biotypes resistant to Groups 2, 4, 9, 14 and […] Read more
Waterhemp is now resistant to seven modes of action and is also showing signs of metabolic-based resistance.
Crops

New threat to weed management

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

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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
Canada fleabane rosette during October.
Crops

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

#PestPatrol with Mike Cowbrough, OMAFRA

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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
In this photo from Mike Cowbrough’s October 2019 Pest Patrol column in Country Guide, light-green waterhemp plants approach the top of a soybean canopy after two ineffective applications of glyphosate. (Supplied photo)
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Group 27 herbicide resistance arrives in Canada

Mesotrione-resistant waterhemp confirmed in Quebec

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Reading Time: 2 minutes A persistent and fiercely competitive weed that has developed resistance to several herbicide groups since its arrival in Canada is now the first in the country to fight off a Group 27 product. Quebec’s Reseau d’avertissement phytosanitaire (RAP) last Friday reported a patch of waterhemp with resistance to mesotrione herbicide in the Haut-Richelieu municipality, in […] Read more
Waterhemp towers above a soybean canopy.
Crops

Pest Patrol: How accurate are plant identification apps when it comes to weeds?

#PestPatrol with Mike Cowbrough, OMAFRA

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Reading Time: 2 minutes Recommendations for plant identification apps were recently making the rounds on social media. Of course it would be nice to accurately identify an unknown weed in your field by taking a picture instead of sending it to an “expert” or a diagnostic lab. However, many of the top-rated plant identification apps are not particularly accurate […] Read more
Figure 4: Waterhemp in soybean.
Crops

Pest Patrol: Dealing with waterhemp and Canada fleabane

#PestPatrol with Mike Cowbrough, OMAFRA

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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.
Crops

The latest on waterhemp

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

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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.
Crops

Pest Patrol: Plan to manage waterhemp in 2020

#PestPatrol with Mike Cowbrough, OMAFRA

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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.
Crops

Recognize the threat of these invasive weeds

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

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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

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