Killing Poa Annua in a Kentucky Blue Grass lawn - Ask Extension
Last fall I applied Tenacity to my lawn. Instead of eradicating the Poa Annua, it seems to have made it more prolific.
Should I try again? Is there...
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Killing Poa Annua in a Kentucky Blue Grass lawn #867866
Asked May 10, 2024, 11:18 AM EDT
Last fall I applied Tenacity to my lawn. Instead of eradicating the Poa Annua, it seems to have made it more prolific.
Should I try again? Is there something I can add to Tenacity to enhance its ability to kill Poa Annua?
Thanks for your assistance
Monroe County Michigan
Expert Response
Hello,
Managing Poa Annua, also known as annual bluegrass, can be challenging. Tenacity (mesotrione) is a selective herbicide that can be effective, but it may require specific strategies to improve its efficacy. Here are some tips based on educational resources:
Timing: It’s crucial to apply pre-emergence herbicides like Tenacity in the late summer or early fall when temperatures drop to a daytime high of 75 °F for four consecutive days. A second application 8 to 10 weeks later may be necessary for continued control.
Mowing: In the spring, when seedheads become visible, mow the lawn frequently at about 2 inches high with a bagger to collect seeds and help prevent their spread.
Alternating Herbicides: Due to the potential for herbicide resistance, it’s recommended to alternate between different types of pre-emergence herbicides with different modes of action.
If you’ve already applied Tenacity and it hasn’t been effective, consider the following:
Soil Conditions: Poa Annua prefers moist and/or compacted soil. Improving drainage and aeration might help reduce its proliferation.
Herbicide Resistance: If Poa Annua has become resistant to Tenacity, switching to a different herbicide with a different mode of action might be necessary.
Integrated Management: Combine chemical control with cultural practices like proper mowing, irrigation, and fertilization to maintain the health and density of your lawn, which is the best defense against weeds.
Remember, complete eradication of Poa Annua is not practical, but reducing it to a tolerable level is a realistic goal.
Additional information is available at these links:
https://hgic.clemson.edu/factsheet/annual-bluegrass-control/
https://archive.lib.msu.edu/tic/golfd/article/2012oct33.pdf
https://archive.lib.msu.edu/tic/holen/article/2012may14.pdf
https://www.canr.msu.edu/ipm/diseases/annual-bluegrass
I hope this helps!
Managing Poa Annua, also known as annual bluegrass, can be challenging. Tenacity (mesotrione) is a selective herbicide that can be effective, but it may require specific strategies to improve its efficacy. Here are some tips based on educational resources:
Timing: It’s crucial to apply pre-emergence herbicides like Tenacity in the late summer or early fall when temperatures drop to a daytime high of 75 °F for four consecutive days. A second application 8 to 10 weeks later may be necessary for continued control.
Mowing: In the spring, when seedheads become visible, mow the lawn frequently at about 2 inches high with a bagger to collect seeds and help prevent their spread.
Alternating Herbicides: Due to the potential for herbicide resistance, it’s recommended to alternate between different types of pre-emergence herbicides with different modes of action.
If you’ve already applied Tenacity and it hasn’t been effective, consider the following:
Soil Conditions: Poa Annua prefers moist and/or compacted soil. Improving drainage and aeration might help reduce its proliferation.
Herbicide Resistance: If Poa Annua has become resistant to Tenacity, switching to a different herbicide with a different mode of action might be necessary.
Integrated Management: Combine chemical control with cultural practices like proper mowing, irrigation, and fertilization to maintain the health and density of your lawn, which is the best defense against weeds.
Remember, complete eradication of Poa Annua is not practical, but reducing it to a tolerable level is a realistic goal.
Additional information is available at these links:
https://hgic.clemson.edu/factsheet/annual-bluegrass-control/
https://archive.lib.msu.edu/tic/golfd/article/2012oct33.pdf
https://archive.lib.msu.edu/tic/holen/article/2012may14.pdf
https://www.canr.msu.edu/ipm/diseases/annual-bluegrass
I hope this helps!
