June 13, 2019

Canola Watch quiz – Herbicide-resistant weeds

1. An 'Economics of Herbicide Resistance' factsheet at manageresistancenow.ca says that approximately what percentage of Canadian farmers are affected by herbicide-resistant weeds?
2. 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?
3. 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 _______________.
4. Important clues that a patch of weeds are herbicide resistant include:
5. If you suspect a patch of weeds is resistant, what can you do?

 

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