The Production and Invasion of
Buddleja davidii in Oregon
Julie Ream with Dr. James Altland
Butterfly bush worldwide
• Grows on old industrial sites and bomb
sites in England
• Problem on river bars, floodplains, and
forest plantations in New Zealand
• Thrives on interstate medians and
rivers in Washington state
Butterfly bush in Oregon
• High value product
in nursery,
landscape, and
retail garden
industry
• B-listed as a
noxious weed
Why butterfly bush was listed
• Very invasive in
certain riparian areas
• Grows on many roads
in Oregon
• As big a problem as
scotch broom for some
foresters
• Thrives where nothing
else grows
My project goals
• To describe in detail the natural sites invaded
by Buddleja davidii
• To determine nursery production practices
that could limit or eliminate invasiveness
Natural sites: materials and
methods
• Site selection:
-Planned to do 3-4 sites of each type
(riparian, roadside, natural area, old
industrial area) in each geographic region
-Geographic regions included Portland
metro area, Coos Bay area, Oakridge area,
and rural North Willamette Valley
Natural sites: materials and
methods
• Marked out the area of each site using set
guidelines
• Established 5 subplots per site for certain
data questions
• Simply answered the other data questions
Natural sites: observations
• Grows everywhere from floodplains to
mountain slopes
• Appears to be a pioneering species
• Densest invasions were on burn sites and
regularly disturbed sites
• Grows mostly in rocky and sandy soils, but
found some in clay soils
• Herbicides control it if applied by hand
Natural sites: results
Drop Page Fields Here
Overall density of bushes vs. type of site
Average of Overall Density of Bushes (bushes/m2)
0.25
0.2
0.15
Drop More Series Fields Here
Total
0.1
0.05
0
Natural Area
Old Industrial
Type of Site
Riparian
Roadside
Natural sites: results
Density of
immature bushes
(bushes/m2)
Density of immature bushes vs. % cover
0.3
0.2
Density of Immature Bushes
(bushes/m2)
0.1
0
0
20
40
Cover (%)
60
80
Nursery production: materials
and methods
• Visited both retail (9)
and production (10)
nurseries
• Asked about
management practices
• Looked for and
collected escaped
seedlings
Nursery production: observations
• Nurseries that did not
cut back over winter
had more escaped
seedlings
• Loose cuttings rooted
themselves
• Most nurseries with
escapees were
wholesale/production
operations
Nursery production: results
• Determined that 37% of nurseries I visited had
escaped seedlings
• Of those 37%, 71% were production nurseries
Nurseries with escaped seedlings (%)
37%
63%
Total % with
escapees
Total % w/o
escapees
More to be done
• Visit more nurseries and more natural sites
• Herbicide trials
• Seed tests
-when seeds are released
-how far wind blows seeds from mother
plant
-if seeds need heat to germinate
Acknowledgements
• HHMI Program
• OAN and the Nursery
Industry
• Dr. Mark Wilson of
Botany and Plant
Pathology Dept.
• Rod Jordan of Moore
Mills Timber Co.
• Jim Carr of Menasha
Forest Products
• Portland Parks and
Recreation
• Dr. James Altland of
Horticulture Dept.
• Steve Wickham of Plum
Creek Forest Products
• Wanda Crannell, BRR
advisor
• Tim Butler and Glenn
Miller of the ODA
• The Nature Conservancy
• Bruce Kelpsas of Helena
Chemical Company