Bermuda grass is not technically considered a weed, but many of us don’t like it and try to get rid of it. Some call it Devil’s grass and other derogatory names. Bermuda is a subtropical grass that always goes “dormant” in the winter. Since it came from tropical climates, it does not tolerate the colder winters in the Bay Area. Seen here is an area of dormant Bermuda.
If your lawn is mostly Bermuda and has little to no green grass in winter, you can scalp and overseed in late fall to establish fescue that stays green all year long, provided you don’t encourage the Bermuda to resume activity by cutting your lawn too short in spring and summer.
If your lawn has Bermuda creeping in, you can control it and beat it back to submission, provided there are no large areas of strictly Bermuda. If it’s mixed into your fescue or bluegrass lawn, try using Turflon D broadleaf weed killer. You’ll likely need to get it online or possibly at your local Ewing Irrigation store. Don’t use Turflon D if your lawn is bentgrass, unless you want to kill the bentgrass. This stuff only works when the target grass is active, so don’t use it on dormant Bermuda!