Invasive species

Scotch broom (Cytisus scorparius, C. striatus)

Photo from King Co. WA

Photo from King Co. WA

Brooms, such as Scotch (or Scots) broom, and gorse are perennial evergreen shrubs that bloom in April-June. They have many slender, erect, dark green angled branches with small leaves and lots of small, pea-shaped flowers. Gorse has distinctive one inch thick spines.

They displace native plants and increase the costs of timber production by invading disturbed site, natural areas, dune and public/private forest lands. The seeds live over 50 years and mature plants produce a lot of seeds requiring long-term maintenance.

The best way to get rid of brooms and gorse is to cut or mow before they go to seed in mid-April. You can pull the smaller plants by hand or by using a weed wrench. Cut back the larger plants and then dig out the roots. It’s best to cut in mid-to-late summer when the plants are stressed.  Fortunately, there are three biological controls:  a beetle, a seed weevil and twig miner are approved for release and have been used effectively in Oregon.

Other species of invasive broom are Spartium junceum, Genista monspessulana and Ulex europaeus.


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