Rubus armeniacus (syn. Rubus discolor) • Class C

Root buds produce trailing green and reddish stems with sharp thorns. Canes bear large green leaves in groups of 3 to 5 and are oval shaped with serrated edges and a pointed tip. Plants bloom from June to August producing clusters of small, white to whitish pink flowers. Canes can root at their tips wherever they touch the ground. Main canes are up to 10 feet long while trailing canes can reach up to 40 feet in length. Flowers develop into blackberries. 

Himalayan blackberry grows very rapidly and is highly invasive and difficult to control. It out-competes native vegetation and prevents the establishment of native trees. 

It is found throughout Pierce County where it forms dense impenetrable thickets.

This troublesome, aggressive plant costs millions of dollars for both control and the estimated impact it has on native plants, wildlife, and livestock.  

The most effective control is prevention. Above all else, prevent plants from going to seed. 

• Blackberries are not easily controlled, but repeated mowing followed by plant and root removal is somewhat effective. First, the plants must be cut down by tractor mounted mowers, brush cutters, or hedge trimmers. Mowing makes the site more accessible too. Then the plants must be removed by digging out the root crowns and large roots with a pick-axe or shovel, and the above ground growth must also be removed. This method will require 5 or more cuttings per year for many years to be truly effective. Hand removal of the root systems is easiest when the ground is very wet (late fall through early spring). 

• Burning the plants, where permissible and then repeatedly pulling or digging out any new starts over several years is also somewhat effective.

• Limited success has been demonstrated from grazing. Goats are the most efficient, but cattle, sheep and even horses are also useful for this method. The animals will not eradicate the blackberries, but will keep them from spreading and keep the size of the infestation from growing larger. Once the mature plants have been removed, chickens have been found to help in the removal of seeds. 

• Herbicide control combined with clearing the site and replanting with native plants is the most successful method of control for blackberries. Canes should be cut down and removed in mid-summer to make the site more accessible. A systemic herbicide like Glyphosate (used in Round-up Pro or Glyfos) is most effective in fall after the plant has produced fruit but before the first killing frost. Be aware, glyphosate is non-selective and will injure any plants that it comes in contact with, including grass. 

When using herbicides, always read and follow all label instructions and obey all label precautions. (Note: pesticide product registration is renewed annually and product names and formulations may vary from year to year.) 

 Download our Flyer or visit Washington State Noxious Weed Control Board Here. Photo by Leo Michels