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Himalayan Blackberry

Posted by cahnrs.webteam | November 13, 2013

Also Known As: Himalaya blackberry, Armenian blackberry

Himalayan blackberry is a Class C Noxious Weed: Non-native plants that are already widespread in Washington State. Counties can choose to enforce control, or they can educate residents about controlling these noxious weeds.

Himalayan blackberry (Rubus armeniacus Focke), a perennial woody shrub native to western Europe, reproduces by seed and vegetatively. Not only does this species propagate from root fragments, stem cuttings, and adventitious buds, but it also sets root and forms daughter plants where its rambling stems touch the ground, resulting in virtual cloning. During the first year, stems (known as “canes”) grow to full length—standing about 15 feet high before arching and trailing off for up to 40 feet. The green to reddish-colored canes are stiff, angular, ribbed, and armed with numerous curved thorns. The first-year canes (“prima canes”) produce no flowers—just leaves. The leaves are round or oval-shaped and have toothed margins; leaves generally occur in groups of 5 on first-year canes and groups of 3 on secondImage_007-year canes. These second-year “flora” canes are side shoots that produce flowers in late spring to early summer. The flowers are small, white to pale pink, have 5 petals and numerous stamens, and occur in clusters at cane tips. The fruits are an aggregate of drupelets that are black when mature, which typically occurs from mid-summer to fall. Each drupe has a single seed that needs sunlight to survive. While flora canes generally die back at the end of the season, the plant continues to vigorously resprout from rhizomes and the root crown. The growing habit and reproductive ability of Himalayan blackberry enables it to create new infestations and form dense, impenetrable thickets, limiting land usage and impeding access of wildlife to water and other resources. By displacing native vegetation, this invasive species reduces diversity of both plants and animals.

Himalayan blackberry can be found in pastures, riparian areas and forest openings, and in disturbed areas such as right-of-way corridors, fence lines, and along field margins. This species can colonize a wide range of soil types so long as the soil is sufficiently moist.

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Control Methods

Maintaining a healthy native plant community is the best way to prevent invasive plants from moving in and taking over. Areas that were once infested with Himalayan blackberry should be cleared out and restored by reseeding desirable competitive plants. Because this blackberry species needs sun to thrive, fast-growing shade trees or shrubs can be planted as a deterrent.

Physical/Mechanical: Young blackberry plants can be hand-pulled, preferably when the soil is moist so that the entire root system can be more easily removed, thereby minimizing plant regrowth. More mature plants can be dug out—again, it is important to remove the root mass. Plant remains should be incinerated or bagged to prevent regrowth from stem or root fragments. Mowing or cutting to remove the plants’ top growth will eventually exhaust the stored energy reserves if repeated often over several years; a more rapid impact can be achieved if mowing or cutting is followed by root removal. Combining mechanical control with herbicide treatments (e.g., applying herbicides to freshly- cut stems or spot-treating regrowth) offers even better control. Whichever method is chosen, continual monitoring of the site will be necessary so that any regrowth can be immediately dealt with.

Chemical: Uncut Himalayan blackberry plants can be treated in late summer or fall with broadcast application of a variety of herbicides, including triclopyr, glyphosate, 2,4-D, and metsulfuron-methyl. Retreatments will probably be necessary. The effectiveness of all foliar-applied herbicides will be greatly diminished if plants are severely moisture-stressed.

More information can be found in the PNW Weed Management Handbook

Use pesticides with care. Apply them only to plants, animals, or sites listed on the label. When mixing and applying pesticides, follow all label precautions to protect yourself and others around you. It is a violation of the law to disregard label directions. Store pesticides in their original containers and keep them out of the reach of children, pets, and livestock.

Biological Control: No biological insect agents are available for control of Himalayan blackberry, primarily due to the potential risk of collateral damage by such herbivorous insects to closely related and commercially important Rubus species. A blackberry leaf rust fungus (Phragmidium violaceum) was discovered on the Oregon coast; it defoliates nonresistant plant populations.

Grazing:  Managed grazing can be used in the same way as mowing to stress and weaken blackberry plants. Goats readily feed on this woody plant.

Questions: contact Steve Van Vleet or phone (509) 397-6290

Photo credits included in PDF

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