Evergreen & Himalayan Blackberry
Rubus armeniacus, Rubus laciniatus
Class C Noxious Weed
- Native to Eurasia, originating from Armenia.
- Introduced as a crop in the late 19th century, it escaped cultivation and has since invaded a variety of sites.
- Himalayan and evergreen blackberry are notorious invasive species around the world costing millions of dollars for both control and in estimated impacts.
- The fruit of blackberry is eaten by many birds, small and large mammals, and harvested by people. Although, it is considered to be less flavorful than the native trailing blackberry (Rubus ursinus).
- Himalayan blackberry cannot provide significant shade for stream water and cannot contribute large woody debris. Overall plant and animal diversity is higher in areas with more diverse native vegetation. The shallow root system compared to native streamside trees and shrubs does not provide adequate bank stabilization and frequently leads to undercutting of streambanks.
- Blackberry’s intense competition for light, moisture, and soil resources inhibit the successional development of forests from pioneer species to mature conifer forests. Native tree seedlings will be outcompeted and as early successional riparian trees die, they will be replaced by a monoculture of blackberry.
- Himalayan and evergreen blackberry are robust, semi-evergreen shrubs that can grow up to 13 feet high, with individual canes extending as much as 23 feet in a single growing season.
- Himalayan leaves are somewhat evergreen, alternately arranged, and pinnately compound divided into 3 to 5 leaflets that are rounded and have toothed edges. Leaves are dark green with a white underside.
- Evergreen leaves are alternately arranged, palmately compound containing 5 leaflets that are deeply divided and lobed with toothed margins. Top of leaf surface is green to dark green and the bottom is pubescent but greenish.
- Stems, referred to as canes, are biennial and can grow 20 to 40 feet long. Canes are stout, green to purplish-red, bearing hooked, sharp prickles with wide bases.
- Flowers are in flat-topped clusters of 5 to 20 flowers, each with 5 petals, white to pink, about 1 inch in diameter. Flowering takes place between June through August.
- Flowers form edible blackberries, each berry is a grouping of small, shiny, black druplets that each contain one seed. Blackberries are about a ½ inch to 7/8 inch in size.
- Himalayan and evergreen blackberry need sun to thrive and cannot tolerate deep shade. They can grow in mixed and deciduous forests but rarely found in dense forest stands except in openings. Grows best in deep, moist, well-drained soils, but tolerate a wide variety of soil conditions. Both can withstand periodic flooding, but not saturated or poorly drained soils.
- Himalayan and evergreen blackberry occupy disturbed opens sites along roadsides, railroad tracks, logged lands, field margins, vacant lots, canals, ditch banks, fencerows, fields, wetland edges and riparian areas.
Reproduction and Spread
- Reproduces by seed and vegetatively.
- Prolific seed producer, a square meter of blackberry can produce 13,000 seeds. Seeds can remain viable in the soil for several years. Seeds are dispersed by birds, small mammals, humans and water. Seedlings require exposure to high sunlight for survival and do not survive well close to parent thicket.
- The primary mechanism for onsite reproduction and spread is vegetative. Blackberry has large root crowns which produce many lateral and smaller, fibrous roots. Roots can penetrate 35 inches into the soil and extend 34 feet in length. As lateral roots spread new canes emerge spreading the population. Root fragments and stem cuttings can also produce new roots and shoots. Canes can also produce adventitious roots at the tips when they touch the ground.
- First year canes develop from buds at or below the ground surface and bear only leaves. Second year cans arise on the first year canes where leaves join the stem, second year canes produce both leaves and flowers. After the second year, the canes die. The dead canes provide a supporting architecture for live canes that sprawl over them, forming a nearly impenetrable thicket.
- Control of blackberry and the replacement with a diverse native plant community is a long-term goal, but thoughtful strategy must be employed to avoid the loss of habitat, increased erosion and loss of streambank stability. The bird breeding season is roughly spring through midsummer, avoid cutting or mowing large patches of blackberry during this time as bird nests may be damaged or destroyed.
- For small patches cut vegetation with loppers and dig up root crowns and major side roots. Make sure to remove as much of the root crown and lateral roots as possible, as fragments left in soil will re-sprout.
- For medium sized patches mow or weed-whack stems into small sized pieces and then dig up roots with Pulaski, mattock or shovel. Spread stem fragments over disturbed soil and/or apply a layer of mulch.
- For large infestations mow or weed-whack vegetation in the winter or early spring as it will remove the possibility of birds, bees and other wildlife forming nests or dens. It will also allow for greater access and reduce the amount work for future control. Several cuttings a year over several years are necessary to exhaust the roots.
- Leave mowed or cut stems on site, avoid raking into piles, the stems will act a mulch reducing the amount of erosion and runoff.
- Mowed blackberry patches can be planted with conifers and other vegetation with dense canopies. As the trees establish ongoing maintenance (physical, mechanical or herbicide) will be necessary to allow trees to dominate the canopy. Once the native canopy is established, their shade will control the blackberry overtime and reduce the need for maintenance.
- Herbicide guidelines are not meant to substitute for the label. Read and follow label instructions and talk with your local county weed coordinator to answer any questions or concerns.
- Mowing or cutting, in combination with herbicide application(s) are the most effective treatment options.
- Mow or cut in winter to mid-growing season. Allow blackberry to re-sprout and grow back to about 18 inches tall and depending on timing either recut or apply herbicide. Apply herbicide to regrowth in mid-summer to early November between fruit and freeze (first hard frost). During this time herbicides are most effective because the plant is sending energy reserves down towards the roots, applying earlier in the season will only result in the plant being burned or top-killed. Timing is especially critical for glyphosate. Triclopyr is less sensitive to timing. Effectiveness drops significantly when plants are drought stressed. Wait at least one week after spraying to mow or cut canes.
- Herbicides containing the active ingredients are effective against Himalayan and evergreen blackberry:
- Non-selective, no residual soil activity.
- Foliar application in late-summer to November, between fruit and freeze. Apply 2% to 4% solution.
- Selective, minimal residual soil activity.
- Foliar application in mid-summer to November, apply 1.5% to 2% solution.
- Pines are very sensitive to triclopyr apply with caution if using in a planting site or ornamental pine trees.
- Bennett, M. (2007). MANAGING HIMALAYAN BLACKBERRY in western Oregon riparian areas. Oregon State University Extension Service, 1–16.
- Washington State Noxious Weed Control Board. (n.d.). Written Findings: Himalayan Blackberry. Retrieved April 8, 2020, from https://www.nwcb.wa.gov/images/weeds/Rubu_armeniacus.pdf
- DiTomaso, J.M., G.B. Kyser et al. 2013. Weed Control in Natural Areas in the Western United States. Weed Research and Information Center, University of California. 544 pp.
Washington State Noxious Weed Control Board. (2008, December 9). Written Findings: Evergreen blackberry. Retrieved April 8, 2020, from https://www.nwcb.wa.gov/images/weeds/Rubus_laciniatus.pdf