Hi Tom, 

Thanks for reaching out! Quack grass is a perennial grass that spreads by rhizomes (underground stems), which unfortunately, makes control quite difficult. There are a few options that may be worth considering: 

1). Accept the quack grass. I understand this is not ideal, but over time, the quack grass may blend into the surroundings and become less noticeable. It is also the safest option for the pollinators and beneficial insects. 

2). Dig out the quack grass, which can be difficult if you are dealing with a large area. Make sure to entirely remove the taproot. 

3). Use a non-selective post-emergent herbicide such as glyphosate. You can spray the patches of quack grass directly or you can wipe glyphosate directly onto the grass. Let the grass grow taller and then use a sponge to wipe the blades (make sure to wear gloves). Glyphosate will require 2-3 applications, and again, this is not the best for protecting pollinators. Remember to always read chemical labels prior to use. Follow the label directions attached to the container you are using - the label is the law. 

Here are a few articles with additional information: 

https://www.canr.msu.edu/news/quackgrass_control_in_turf (see here for a section on mowing and fertilizing your lawn to defend against quack grass)

https://extension.umn.edu/weeds/quackgrass

Good luck!