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Poa Annua #885451

Asked September 16, 2024, 2:52 PM EDT

Good afternoon. I'm curious how best to treat post emergent poa annua in a 4 cultivar perennial rye lawn. I'm in the kalamazoo area, soil test is fine, I renovated with good soil/sand, irrigate regularly but based on ETO, treat with ammonium sulfate and natural things like kelp, molasses etc. I didnt blanket spray herbicide or pre-emergent this year but have been spot treating with a speedzone/quonclorac blend. I also have a halosalfuron herbicide for yellow nutsedge. I'm wondering my options short of doing a glyphosate spot treatment. Caveat being I overseeded on August 18th. I've read on the prodiamine label that I need to wait 60 days after overseed before application. I have resisted using tenacity as a blanket spray due to my lawn being all perennial rye, Tenacity tends to damage rye according to its label, however I have come to terms that I may need short term visual damage if mesotrione is the answer. I'm curious what you recommend in terms of what I can do with our average first frost being approx a month out. Thanks so much for your time!

Kalamazoo County Michigan

Expert Response


Hello,

Given your situation, here are some recommendations for managing post-emergent Poa annua in your perennial rye lawn:

Spot Treatment with Mesotrione (Tenacity):

While Tenacity can cause temporary bleaching in perennial ryegrass, it is effective against Poa annua. Given your overseeding date (August 18th), you can use Tenacity as a spot treatment to minimize damage to your lawn. The bleaching effect is usually temporary, and the grass should recover.

Post-Emergent Herbicides:

Since you have been using a SpeedZone/Quinclorac blend, continue spot-treating with this combination. It is effective against various broadleaf and grassy weeds, including Poa annua.

Pre-Emergent Herbicides:

As you mentioned, Prodiamine is a good option but requires a 60-day wait after overseeding. You can plan to apply it later in the fall or early spring to prevent Poa annua from germinating next season.

Cultural Practices:

Maintain proper mowing height and avoid overwatering, as Poa annua thrives in moist conditions. Deep, infrequent watering is more beneficial.

Non-Chemical Control: (I have to add this as an option – HA HA!)

Hand-pulling can be adequate for small infestations. Ensure you remove the entire root to prevent regrowth.

Halosulfuron for Yellow Nutsedge:

Continue using halosulfuron for yellow nutsedge control. It is practical and won’t interfere with your Poa annua treatments.

Given the average first frost in your area is about a month away, focusing on spot treatments and cultural practices now will help manage the Poa annua without causing significant damage to your newly overseeded lawn.

Here is the reference from MSU on Poa annua:

Annual Bluegrass - Turf (msu.edu)

If there is something I am missing, please let me know!

I hope this helps!



An Ask Extension Expert Replied September 16, 2024, 5:23 PM EDT

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