Hello,

Managing a lawn with an infestation of annual bluegrass (Poa annua) can be challenging, but with the right approach, you can regain a healthy turf. Here’s a comprehensive plan based on the information from educational sources:

Fall Pre-Emergent Application:

Apply a pre-emergent herbicide in late summer or early fall when daytime temperatures drop to a high of 75°F for four consecutive days.

MAKE SURE YOU READ THE LABEL AND FOLLOW THE DIRECTIONS ON THE HERBICIDE!

A second application may be necessary 8 to 10 weeks later for continued control.

Pre-emergent herbicides can prevent the germination of Poa annua seeds, but they won’t leave the area bare as they don’t kill existing plants. More information at this link:

Annual Bluegrass Control | Home & Garden Information Center (clemson.edu)

Reseeding After Pre-Emergent:

Generally, seeding should be delayed until 30 days after the pre-emergent application. More information at this link:

Spring Lawn Care | Good Growing | Illinois Extension | UIUC

However, for a more specific timeline, it’s best to follow the label directions of the product you use, as different herbicides have varying residual effects.

Killing and Reseeding Large Infested Areas:

If you decide to kill off the large, infested areas in the fall, you can reseed with your desired grass type.

For less infested areas, applying the pre-emergent and overseeding in the spring might be a viable strategy.

Choosing the Right Grass for Reseeding:

When considering reseeding with a spreading fescue like Rhizomatous Tall Fescue (RTF), it’s important to note that RTF can spread by short rhizomes, which may provide better coverage and density compared to tall turf bunch grasses.

The process of reseeding with RTF would be similar to other fescues, but the spreading nature of RTF might offer improved self-repair and coverage over time.
More information at this link:

Understanding Those Fescues // Missouri Environment and Garden News Article // Integrated Pest Management, University of Missouri

Remember, the success of these strategies can also depend on proper lawn maintenance practices such as mowing, irrigation, and fertilization to encourage the growth of the desired turfgrass and discourage weed establishment. Always follow the label instructions of any herbicide you use. 

I hope this helps!