Question of the Week – Number 1: June 27, 2019

“How can I stop my neighbor’s St. Augustine from invading my bermuda lawn?”

This used to be a really easy question to answer. That was before we lost MSMA as a weedkiller alternative. It would kill unwanted grasses, St. Augustine included, in bermuda turf without harming the bermuda. But it’s been gone for 8 or 10 years and now the scene changes.

Your best bet is to keep the St. Augustine ever from getting a roothold within your bermuda. Install an edging strip of redwood or other 1-inch lumber flush with the soil surface and use your line trimmer to feather an edge down to it. Trim off the St. Augustine runners as they attempt to spread over the top of the strip.

Plan B, the more involved of the two, would be to develop an extended flower and shrub bed out from the house toward the street and let it be your edging strip. Sure, it would divide off the neighborhood, but at least it would stop the St. Augustine.

And finally, in a situation like you see in the photo, where St. Augustine has already started to become the dominant grass, you’ll need to pull out as many runners as you can at a time when the soil is very wet after irrigation or rain. Wait a week or two, then spray any remaining runners with a glyphosate-only herbicide in a pump sprayer. Be as precise as you can in your application. Sure, it’s going to put ribbons of browned grass where it kills both St. Augustine and bermuda, but the bermuda will quickly fill in behind it.