Himalayan Blackberry and Evergreen Blackberry
Rubus armeniacus (syn. Rubus discolor) and Rubus laciniatus

Himalayan blackberry and evergreen blackberry are Class C noxious weeds on the Washington State Noxious Weed List.  They are widespread throughout King County and the rest of Western Washington and control is not required.  However, control is recommended in protected wilderness areas and in natural lands that are being restored to native vegetation because of the invasiveness of these species.

Impacts and Distribution

Himalayan and evergreen blackberry are European species that are highly invasive and difficult to control. Originally introduced for fruit production, they are now naturalized and widespread throughout the Pacific Northwest.

These invasive blackberry species out-compete native understory vegetation and prevent the establishment of native trees that require sun for germination such as Pacific Madrone, Douglas Fir and Western White Pine. Dense, impenetrable blackberry thickets can block access of larger wildlife to water and other resources (not to mention causing problems for people trying to enjoy parks and natural areas).

Himalayan and evergreen blackberry are abundant along rivers and wetland edges in King County, often blocking access to these areas. In addition, blackberry lacks the deep, bank stabilizing roots of native wetland shrubs and trees. Riversides covered with blackberry often indicate degraded conditions and may mask eroding banks.

In an invasive weed survey of the relatively pristine Middle Fork Snoqualmie Valley, Himalayan and evergreen blackberry covered more area than all of the other invasive species combined. Similarly, in Seattle Urban Nature’s plant inventory of Seattle’s public forests, Himalayan and evergreen blackberry were found to be the most invasive species in Seattle's forests.

Description

• Robust, thicket forming shrub
• Stout, arching canes with large stiff thorns
• Up to 15 feet tall; canes to 40 feet long
• Small, white to pinkish flowers with five petals
• Large, black berries (edible and tasty!)
• Himalayan blackberry leaves are palmately compound with large, rounded to oblong, toothed leaflets usually in groups of 5 on main stems
• Evergreen blackberry (also known as cut-leaf blackberry) has deeply incised leaflets
• Trailing stems usually have leaflets in groups of three
• Blackberry canes root at the tips, creating daughter plants
• Main plants have large, deep, woody root balls that sprout at nodes
• Can be distinguished from the native trailing blackberry (Rubus ursinus) by its tall, arching reddish-brown canes, much more robust plants, rounder leaflets (or deeply incised leaflets for evergreen blackberry), and larger fruits and flowers

Reproduction and Spread

• Blackberry reproduces by seed and vegetatively by rooting at stem tips and sprouting from root buds
• Plants begin flowering in spring with fruit ripening in midsummer to early August
• Both types of blackberry are somewhat evergreen in this area, although Himalayan blackberry will die back with colder temperatures
• Daughter plants form where canes touch ground
• Seeds remain viable in the soil for several years
• Fruiting stems generally die back at the end of the season, but non-fruiting stems can persist for several years before producing fruit

Control

Blackberry can be controlled by digging, mowing, herbicide, plowing, and/or livestock grazing (especially goats). Removal of top growth by mowing, cutting or grazing with goats will eventually kill blackberry if done regularly and over several years. Cutting followed by digging up root crowns is much more effective than cutting alone. Blackberry can be controlled with herbicides, but product labels should be followed carefully - different products need to be used at different times and may pose different risks to the user and the environment.

Make sure to have a long-term plan to ensure success, protect native and beneficial species while doing the control, and start in the least infested areas first and then move into the more heavily infested areas.

Himalayan and evergreen blackberry photos - click for larger images