Integrated Control of Scotch Broom: Techniques and Strategies

Scotch broom continues to be a pest plant on Ft. Lewis and throughout western Washington. On Ft. Lewis,
Scotch broom degrades open training lands. It also eliminates many of the natural resources from these
lands. Both native plants and animals are displaced by the dense monocultures that Scotch broom forms.
In addition, Scotch broom adds nitrogen to the soils and increases fire intensities. Both of these actions
alter natural processes and can lead to the invasion of additional pest plants. Overall, Scotch broom is a
severe threat that degrades both natural resources and military training. The effective and efficient control
of this pest is a priority.

The control of Scotch broom requires a long-term effort. Scotch broom seeds can survive in the soil for
several decades. This means that regular follow-up treatments must be applied and that Scotch broom
plants must be controlled before they begin to set seed in their third year of life. In addition, younger
Scotch broom has the ability to re-sprout when cut. This makes the complete control of younger Scotch
broom more difficult. The combination of long seed life and the re-sprouting of young plants require an
integrated strategy that utilizes a variety of control techniques performed on a consistent basis.

There are two keys to a successful Scotch broom control program. The first is to minimize the amount of
seed produced, which can be accomplished by using reliable control efforts every 2-3 years. The second is
to maximize mortality rates matching control techniques to the density and size of the broom plants.
Regular application of effective techniques will result in the rapid decline of the extent population of
Scotch broom on a site. Along with this decline, the amount of resources applied in each control effort can
also be reduced. Eventually, control of only a limited amount of seed sprouting out of the seed bank will
be needed.