Blackberry Plants - Biology
The common weedy blackberry in the Pacific Northwest is the Himalayan blackberry, Rubus discolor. Despite its name, it is a native of Europe. It is widespread in southern British Columbia, Idaho, Washington, Oregon, and northern California and is also common in the northeast U.S.2 It thrives in disturbed moist areas and at all elevations up to 5,000 feet.(3)
Blackberry branches, called canes, are known for their stout thorns. Canes are biennial, producing lateral branches which bear fruit in their second year.(2)
Himalayan blackberries are robust. They can be 10 feet tall and their canes can grow as much as 20 feet in a season. Trailing canes can root where they contact the soil, producing “dense, impenetrable thickets.”(2)
At the base of a blackberry cane is an irregularly shaped crown. Roots extend from this crown, and have been recorded up to 30 feet long!(4) Blackberry seeds are transported by birds and mammals that eat the fruit. Seeds can remain viable in the soil for several years.(5)
New plants can also develop from crowns and underground stems.(1) There are several native blackberry species in the Northwest.(3)
Focus on Desirable Plants
Start a blackberry removal project by thinking about what plants you want in the area that’s now blackberries. Planting desirable seeds or nursery stock once the berry plants are removed is often critical. Blackberry removal techniques are site specific. What works well in one site might not be compatible or effective at a different site. Choose a technique that fits in with your goals for the site after the blackberries are gone.
Don’t Get Discouraged!
Many of the characteristics of the Himalayan blackberry make this plant difficult to remove. Don’t get discouraged when you tackle a blackberry removal project without herbicides. Remember that, according to the University of California, “blackberry plants usually regrow following herbicide application.”(1) All techniques for removing blackberries require persistence. Plan to follow up your removal work.
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1. University of California Agriculture and Natural Resources. 2002. Wild blackberries. Pest Notes Publ. 7434. www.ipm.ucdavis.edu.
2. Oregon State Univ. Horticulture Dept. Undated. Landscape plants: Images, identification, and information. Vol. 3.
3. Ertter, B. 1993. Rubus. In The Jepson manual: Higher plants of California, ed. J.C. Hickman. Berkeley: University of California Press.
4. Amor, R.L. 1974. Ecology and control of blackberry (Rubus fruticosus L. agg.) Weed Res. 14: 231-238.
5. Brinkman, K.A. 1974. Rubus L.: Blackberry, raspberry. In Seeds of woody plants in the United States. Agriculture Handbook No. 450. C.S. Schopmeyer, ed. Washington, D.C.: Forest Service, U.S. Dept. of Agriculture. Pp. 738-743.
Oregon State Univ. Extension. Undated. Blackberries take time and persistence to control. Gardening Information. http://www.eesc.orst.edu/agcommwebfile/garden/Fruit/blackberries.html.
The Nature Conservancy. 1989. Elemental stewardship abstract for Rubus discolor (Rubus procerus), Himalayan blackberry. http://tncweeds.ucdavis.edu/esadocs.html.
AgResearch Crown Research Institute. 1998. Goats for weed control. AgFACT No. 240. | www.agresearch.cri.nz/agr/pubs/agfact/pdf/240goatsforweedcontrol.pdf.
Vere, D.T. and P.J. Holst. 1979. Using goats to control blackberries and briars. Agricultural Gazette of New South Wales 90; 11-13.
Kiester, E. 2001. Getting their goats. Smithsonian Magazine (October). www.smithsonianmag.si.edu.