A randomized-stratified survey of 315 sites in Manitoba found that, overall, 58% of the kochia populations tested were glyphosate-resistant, while 1% were dicamba-resistant. There was a rapid increase in glyphosate-resistant kochia over a five-year time frame, and the survey also confirms the first cases of...

Action and economic thresholds for volunteer Roundup Ready canola in Roundup Ready soybean were determined. Economic thresholds of less than 0.5 plants/ft2 (<5 plants/m2) highlight the highly competitive nature of volunteer canola in soybean crops. Volunteer glyphosate-resistant (GR) canola is a challenge for Roundup Ready soybean...

A 2018 survey found that Russian thistle populations collected in Manitoba did not exhibit resistance to acetolactate synthase inhibitors (tribenuron/thifensulfuron; Group 2), synthetic auxins (2,4-D ester or fluroxypyr; Group 4), or glyphosate (Group 9). The status of herbicide-resistant Russian thistle in Manitoba was unknown, so a...

In a 2017 Alberta survey, 13% of the kochia populations sampled were fluroxypyr-resistant. Only 4% of the populations were both fluroxypyr- and dicamba-resistant, indicating that different mechanisms may confer resistance to these herbicides. When combined with estimates of dicamba resistance, about 28% of kochia populations...

Combining a post-emergent herbicide application with a subsequent pre-harvest glyphosate application resulted in the best dandelion control. Growers should consult with their oat buyer to ensure that they will accept oats treated with pre-harvest glyphosate. The objective of this study was to determine if cultural practices...

Weed surveys show that the incidence of herbicide-resistant grassy and broadleaf weeds continues to increase across the Prairies during the survey periods of 2014 through 2017. The perceived cost of herbicide resistance was estimated at $13.36 per acre. Regular surveillance for herbicide-resistant (HR) weeds has been...

The most effective and consistent treatments for glyphosate-resistant (GR) kochia management included Authority (sulfentrazone) applied pre-emergence, post-emergent Enforcer D (fluroxypyr/bromoxynil/2,4-D) at the high label rate, and post-emergent Infinity (pyrasulfotole/bromoxynil). Glyphosate-resistant (Group 9) kochia has rapidly spread across Alberta since it was first discovered in 2011 in...

All 15 PRE followed by POST herbicide combinations provided better control of volunteer canola compared with the glyphosate-only control, but tribenuron (i.e. Express SG) followed by bentazon, and tribenuron followed by imazamox plus bentazon (i.e. Viper ADV) provided solutions that were low cost, registered in...

Effective pre-emergent or pre-emergent followed by post-emergent (two-pass) programs tested in this research on the U.S Great Plains should be proactively utilized by growers to manage glyphosate/dicamba resistant kochia in Roundup Ready 2 Xtend (glyphosate/dicamba-resistant) soybean. A similar approach may prove useful for western Canadian...