Canola Watch quiz – Herbicide-resistant weeds

June 13, 2019 - Issue 11

1. What are we seeing in this photo?

2. An 'Economics of Herbicide Resistance' factsheet at manageresistancenow.ca says that approximately what percentage of Canadian farmers are affected by herbicide-resistant weeds?
3. Patches of herbicide-resistant weeds usually develop through a process of 'selection'. The website manageresistancenow.ca describes the development of herbicide resistance in four steps. Step 1: A very small number of weeds in the populations are naturally resistant to certain types of herbicides. Step 2: When the herbicide is used, it controls almost all the weeds in a population. Step 3: Survivors are resistant to the herbicide and lead to the next generation of resistant weeds. What does the website describe as Step 4?
4. Group 1 clethodim can be tank mixed with Group 10 glufosinate to enhance grassy weed control in Liberty Link canola, but what if the field has a lot of Group-1 resistant wild oats? Growers can improve glufosinate activity on grassy weeds by using the 10-gallon-per-acre water rate and _______________.
5. Important clues that a patch of weeds are herbicide resistant include:
6. If you suspect a patch of weeds is resistant, what can you do?

 

Canola Watch