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The Dirt | Weed of the Month September 2025 | False Brome (Brachypodium sylvaticum)

"False brome is a noxious weed in Oregon. It invades forests. Manage by digging/mowing or herbicide. Benton County CWMA info."
A patch of green grass growing among leaves and foliage on the ground.
False brome tuft. Photo credit: Bruce N. Newhouse
Close-up of tall grass with thin, pointed blades against a blurred leafy background.
False brome florets attached directly to main stem. Photo credit: Graham Calow.
Close-up of green grass stems with fine hair-like structures, against a blurred background.
Hairs on False brome leaves. Photo credit: Barbara L. Wilson,
A patch of green grass growing among leaves and foliage on the ground.
Close-up of tall grass with thin, pointed blades against a blurred leafy background.
Close-up of green grass stems with fine hair-like structures, against a blurred background.

Our September Weed of the Month is False brome (Brachypodium sylvaticum). False brome is notorious for invading forest understories and edges. It is a uniquely problematic grass to control since it has a high shade tolerance and thrives in shady areas where other grasses will not.

This grass germinates in the late fall and early spring. is identified by its yellow/lime green color leaves that are covered in fine hairs, as well as drooping seed heads when mature. Another identifier is the fact that its spikelets are directly attached to the main stem (second photo).

The Oregon Department of Agriculture (ODA) lists False brome as a List-B noxious weed in Oregon. It vigorously outcompetes other vegetation when left unmanaged and can even be a threat to Oregon white oak regeneration. For these reasons, it is an important species to control if detected early. For small infestations, manually removing the entire grass tuft including roots is recommended. If you have a large infestation of false brome, you may want to consider the use of a grass-specific herbicide for control.