Controlling Roughstalk Bluegrass (Poa trivialis) in Fescue Lawns: Difficult Choices

Q: Our fescue lawn was diagnosed with invasive winter grass Poa trivialis, consuming over 60% of the lawn. What would you do?

You won't like my answer.

Poa trivialis (roughstalk bluegrass) and Poa annua (annual bluegrass) are cool-season grasses. Both die out or go dormant in summer heat. Poa trivialis is perennial and much harder to control.

Current research on new herbicides can suppress roughstalk bluegrass, but nothing selective enough to kill it without harming lawn grass.

So killing everything with glyphosate and reseeding is sometimes the only option.

Hard to advise in late spring. You could kill everything and reseed fescue, but fescue won't survive July heat without strict watering. Or mow the bluegrass until fall, pray for a mild summer, then kill bluegrass in September and reseed fescue.

ID and Control of Bluegrasses