May 29, 2024

QUIZ – Weed ID, part 2

Five more weeds to identify. Hopefully you find these a little more challenging than last week’s quiz. Take the quiz to pick up a few scouting and management tips.

1. Glyphosate resistant _______ results from a type of mutation in the plant called target site amplification or gene overexpression. The plant makes more copies of the enzyme that glyphosate attacks. With more copies of the enzyme, it takes more and more glyphosate to take out each copy of the enzyme and kill the plant. It doesn’t take much amplification before glyphosate is no longer effective. As shown in this actual test result, this particular _____ plant had 28 copies of the enzyme. It only takes three copies to be considered resistant. (Fill in the blank.)
PSI Labs test result
Actual result from a PSI Labs test.
2. This is annual sow thistle, a common weed on the Prairies. In-crop weed control of annual sow thistle is possible. However, perennial sow thistle control is more difficult at this time. What is an easy way to tell them apart in late May?

Spiny annual sow thistle
Spiny annual sow thistle
3. At the Weed ID Clinic in Carman, Manitoba last week, Kim Brown, Manitoba Agriculture’s weed specialist, said this weed is rising in abundance on the Prairies and is starting to move out of the ditches and into fields. When weeds behave like this they seem to become herbicide resistant fairly quickly, Brown says. What is it? 
4. These three weeds can be hard to tell apart. Weed "2" is common. The other two close relatives are abundant in Ontario and the U.S. northern plains, and are moving into the eastern Prairies. The two close relatives are often glyphosate resistant. What is the common species shown in photo 2? (We’ll name the other two in the answer.)
5. Group-4-resistant populations of this weed were found in Alberta as far back as the 1990s. Weed specialists recommend a balanced approach when spraying this weed, and not relying on Group 4s to do all of the work. What weed is this?

 

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