Common Name: Himalayan blackberry
Scientific Name: Rubus discolor
Code: RUDI2
Group: Dicot
Family: Rosaceae
Growth Habit: Shrub
Duration: Perennial

What does it look like?

The thorns on this species are large woody arcs, similar to those on a rose, with groups of three to five leaves (usually five) and are a much lighter color on the underside than the top. Flower petals are 3/8 to 5/8 inch long and vary in shades of pinkish to white. Himalayan blackberry produces flowers from May to August. The fruit are shiny, black, oblong berries.

This species is similar to the native Pacific blackberry (Rubus ursinus) plant but can be distinguished by its thicker, 5-angled arching stems (see photo left) with thorns that are larger and further apart. Pacific blackberry has smaller, rounder stems with numerous small, straight prickles that can be easily pushed over, and its leaves occur in a three-leaflet pattern exclusively.

Where does it grow?

Native to Eurasia, Himalayan blackberry is now one of the most ecologically-threatening invasive plant species in the state of California. Himalayan blackberry is common along roadsides, creek gullies, river flats, and fence lines (Parsons and Amor 1968 in Bossard 2000). It is also common in riparian areas because it requires adequate soil moisture and prefers disturbed, wet sites.

Is it in our watershed?

Himalayan blackberry grows extensively throughout the Mattole watershed and often grows along roadsides, fences, and open fields. This species is extensive in Petrolia. It also grows along many county roads including the Mattole Road, Wilder Ridge and Briceland/Shelter Cove Road, and around Whitethorn.

Why is it a problem?

Himalayan berry is an extremely aggressive invader that forms dense thickets often widening 10 or more feet a year, shading out all other native plants in its path (BLM, 2003). This blackberry is very difficult to control because it is so successful at vegetative reproduction and because birds also eat and disperse the seeds. It is notorious for invading and rapidly spreading through rangelands and pasture areas, and decreasing the amount of useable land in these areas (Bossard, 2000).

How do you get rid of it?

Manual Control: One method is to cut the canes or stems and then grub the roots. New growth will resprout from the roots and seed, so it is necessary to return each year to pull out new starts until it is obvious that eradication has been successful. (NPS, 2001). Small plants can be controlled with a hand hoe by cutting off the tops or stirring up the surface soil to expose the seedlings to the sun. This is most beneficial in the maintenance phase.

Manually operated tools such as brush cutters, weed-eaters, power saws, axes, machetes, loppers and clippers can cut canes and stems. This removes the dense, armed vegetation that exists above ground and allows access to the root crown. Cutting the canes alone is not a successful removal technique, unless repeated multiple times each year. It is an important control technique, especially when combined with other methods

Mechanical Control: Heavy machinery is highly successful at removing the majority of aboveground vegetation. It is fairly inexpensive to control woody vegetation on gentle topography without large obstacles (i.e.: rocks, logs). However, this is non-selective and often removes all of the vegetation in the area and is not successful unless it is part of multiple cuttings. If only one cutting is possible, it is best to do it when the plant is flowering; at this time the food reserves in the roots have nearly been exhausted and the seeds have not yet been produced (Soll, 2004). Follow-up is extremely important in the eradication of Himalayan Blackberry, otherwise new growth can resprout from the roots and grow back in even thicker brambles.

Prescribed Burns: Prescribed burns have successfully removed mature standing plants, but it is not recommended as a stand-alone treatment. This technique requires multiple burns or cuttings to exhaust seed bank combined with re-vegetation of native, fast-growing shade tolerant plants.

Habitat Manipulation: Himalayan Blackberry is usually intolerant of shade. Planting native tree and shrub species while removing blackberry can help native species regain control (Soll, 2004).

Grazing: This is an effective control technique, especially on steep slopes and areas where mechanical removal is not an option. Goats are successful at controlling species, such as Himalayan berry, within the first few years of growth but not in mature stands. Effective use of goats requires tethering them and limiting their range to force them to graze on the blackberries and no other plants.

Author:
Unity Peterson, Invasive Plant Program Coordinator, Mattole Restoration Council, Petrolia, CA.

Photographs:
Unity Peterson, 2004

References:
BLM 2000. Noxious Weeds of the Arcata Field Office. Bureau of Land Management. http://www.ca.blm.gov//arcata/arcweeds.html

Bossard, CC., J.M. Randall and M. Hoshovsky. (eds.) 2000. Invasive Plants of California’s Wildlands. University of California Press, Berkeley, CA. Online version: http://groups.ucanr.org/ceppc/Invasive_Plants_of_California's_Wildlands/

NPS 2001. Exotic Plant Species List. Scientific and Common Names of known Exotic Plant Species in the Redwood National and State Parks. National Park Service. http://www.nps.gov/redw/epsplist.htm

Soll, Jonathan. Brian Lipinski, editor. Controlling Himalayan Blackberry in the Pacific Northwest. The Nature Conservancy. 2004.
http://tncweeds.ucdavis.edu/moredocs/rubarm01.pdf