Poa trivialis is a perennial grass, which spreads by stolons and seeds. It is challenging to deal with since it cannot be effectively controlled by any selective herbicides currently on the market. It seeds once a year which is happening now. Later in the season, it blends in with fescue grass.

The best way to manage Poa trivialis is to use a systemic herbicide, namely one containing the ingredient glyphosate. Glyphosate can be found in many products, but originally only in Round-Up. This will leave dead patches that will have to be reseeded. Total control of this weed is very doubtful. Please see the following information from our website, http://extension.umd.edu/hgic/topics/roughstalk-bluegrass.

Annual bluegrass can be controlled with a pre-emergent herbicide applied in mid-August/early September before the seeds germinate. See our website for more options. https://extension.umd.edu/hgic/topics/annual-bluegrass

A healthy, dense, vigorous lawn is the best defense against weeds. Practices that contribute to fewer weed problems include:

• Soil testing to check soil fertility and pH
• Proper mowing height and frequency 
• Fertilizing at the recommended times
• Overseeding in the fall to thicken up the lawn