EVERGREEN blackberry (Rubus discolour)

&

           HIMALAYAN blackberry (Rubus laciniatus)

 

      

 

Invasive implications

Himalayan and evergreen blackberry species are introduced from Eurasia (~1885) and currently dominate many regions of the Pacific Northwest. Both tend to form impenetrable thickets due to spreading vines with very prickly stems. Himalayan blackberry is generally more widespread than its evergreen cousin. However, both species are a cause for concern as they are extremely competitive on disturbed sites, degrading the quality of riparian habitats along with fence lines, roadsides, and forest edges. In the Lower Mainland, blackberries deteriorate valuable stream habitat by preventing the establishment of deep-rooted native shrubs, which are a critical for healthy streams, providing food, shade, and bank stability. However, blackberry shrubs do offer limited food, nesting sites, and wildlife cover (and make great blackberry pies!). Evergreen and Himalayan blackberry are extremely difficult to remove as they grow very fast and have efficient reproductive success. Nevertheless, stands can be controlled through vigorous cutting, planting, and monitoring efforts as outlined in the sections below.

 

Identification - Evergreen

Spring

Summer

Winter

  •  young stems are erect but arch as they lengthen

  •  forms an erect, spreading or trailing evergreen shrub
  •  eventually touch the ground and root at the nodes
  •  leaves turn burgandy colour throughout winter
  •  leaves can be sparse

Leaves

Stem/Roots

Flower/Fruit

  •  3-5 leaflets, alternate, deeply incised
  •  green to greenish-red above and paler below
  •  hairy undersides
  •  mature stems grow up to 12 meters in length (3 meters in height)
  •  stems are about 1.5cm thick, reddish-green
  •  thorns pointing downward

 

  •  flowers are white to pink with 5 petals (9-14mm long), flowering June - August
  •  fruit turn shiny black about 2 cm in length with many hard seeds (edible but not as good as Himalayan)
  •  fruits ripen in August - September, seeds disperse in October - November

 

Identification - Himalayan

Spring

Summer

Winter

  •  new stems grow from buds underneath surface and are sterile (only leaves, no flowers)

  •  produce leaves and flowers in year two

  •  grow up to 3 meters tall and length of 10 meters or more
  •  can form a "wall" of impenetrable thickets
  •  seeds disperse in fall
  •  growth slows but leaves persist

Leaves

Stem

Flower/Fruit

  •  evergreen leaves, 3-5 oval leaflets
  •  shiny green on top, pale green underneath
  •  curved prickles on edges of leaflets
  •  flowers have 5 broad petals, commonly white, also rose or reddish coloured, 2-2.5cm across
  •  fruit is rounded, shiny black, up to 2cm long ripening August-September

 

Similar Plants

Evergreen or Cut-leaf blackberry is very similar to trailing blackberry (Rubus ursinus). Rubus ursinus is a vine that "trails" along the ground, often tangling in the feet of passerby's. This vine can also form thickets but is usually far less invasive than Himalayan or evergreen blackberry. Some distinguishing features of trailing blackberry are its small stem size (~0.5cm), white waxy coating on the stem, deciduous leaves (in 3's), and its tendency to lay on the ground. Salmonberry (Rubus spectabilis) is another similar looking native plant that is abundant and vital to the Lower Mainland. It is distinguished by smaller zigzagged stems, red-pink flowers, golden-brown shredding bark, and yellow or reddish edible berries.

 

Trailing blackberry (Rubus ursinus) Salmonberry (Rubus spectabilis

  

Key Features

Blackberry grows in relatively open, disturbed, and moist sites such as stream sides, ditches, forest edges, and pastures. It prevails in relatively wet coastal climates with annual rainfall near 76cm per year. Canes of Rubus discolour can grow up to 7 meters in a single season! Stems initially grow upwards but begin arching when they reach lengths of several meters. At this point, stems bend down towards the ground.

Reproduction occurs by both vegetative and sexual means. Canes can root when the tips touch the ground, forming a dense network of prickly thickets. Blackberries also propagate via root pieces and cuttings and can branch daughter plants from mature canes. Shoots can arise from underground runners that persist up to a meter deep and over 10 meters long. Blackberry shrubs produce numerous seeds per berry that are spread by birds and other animals. Himalayan thickets can yield up to 13,000 seeds per square meter.

Wild blackberry flowers are pollinated primarily by bumblebees and honey bees. The flowers can be self-pollinated but fruit set is increased by cross pollination.

 

Control Measures

Rubus laciniatus and Rubus discolour are difficult to manage and have become quite common in both the Lower Mainland and Vancouver Island. There are conflicting reports as to the 'best' control practices. For example, some sources support fire control methods where others deem this practice as futile, arguing there is inefficient root kill. Physical methods such as hand-pulling, cutting, disking, and shading are popular. The bottom line when managing blackberry is to ensure long-term control by shading these species out with native plants. Otherwise, the reproductive invasiveness of blackberry will likely allow it to prevail. Chemical methods are often used in conjunction with non-chemical methods. For example, some report success by first cutting large stands using mechanical removal before manually cutting and painting each stem with herbicides. To date, no biological control organisms have been successfully introduced, largely because of risks posed to commercial and native Rubus species.

 

Non Chemical Control

  Hand pulling/digging Mechanical Removal Cutting
How Remove the entire stem and root system using hand or digging tool Use machinery to completely uproot or cultivate plants Use manually operated tools - laupers, machetes, clippers, power tools, etc. to remove above ground portions
When Young plants up to 1m, when soils are moist to completely remove root system Before planting competitive plants or applying herbicides Best time is when the plants begin to flower (reserve food supply nearly used up)
Duration

 

Until plant is eradicated from the area Should only be performed once to minimize soil disturbance. At least three years to kill the root systems of the plants
Pros/Cons Only effective where there are a few plants in their first year of growth, highly selective Can undertake larger areas but non-selective and inappropriate for sensitive ecological areas, may cause erosion Effective but insufficient for complete control, labour intensive

 

Non Chemical Control

  Prescribed Burning Grazing
How Pre-spray area with herbicides to kill and desiccate plants, then broadcast burn Use large numbers of goats, sheep, cattle, or horses for light to intensive grazing
When Before planting native competitors or performing other control methods, usually in fall or spring Selectively throughout year to minimize soil compaction
Duration

 

If strictly burning, will require subsequent burning to exhaust soil seed bank and underground food reserves Dependent on whether planting competitive species or using grazing as a sole control practice
Pros/Cons Requires several treatments if used as a sole control practice Less costly than many mechanical or chemical control methods, must protect desirable species as animals are often "non-selective"

 

Chemical Control

 

Spot Application

Broadcast Application

How

Glyphosate, triclopyr and 2,4-D are effective against blackberries

Cut stump treatment - apply herbicide directly to cross section and edges of freshly cut stems

Stem injection - inject herbicide into wound or cuts

Basal sprays - uses backpack sprayers to add high herbicide concentrations to base of stems

Herbicide pellets - scatter at base of shrubs (see Nature Conservancy)

Do not spray so herbicide is dripping off leaves. Glyphosate, triclopyr and 2,4-D can be used to kill blackberries
When Cut stump treatment within 15-20 minutes of cutting in late spring, basal sprays work best in fall, pellets are effective in fall and spring Plant leafs should be in full leaf, spray after seed is set for best results (mid-August into September). Take care to apply on a cool, cloudy day to prevent evaporation and spread of herbicides.
Duration Until re-sprouting no longer occurs Repeat applications if necessary to completely remove plants
Pros/Cons Highly selective, some herbicides are very effective but will not provide long term control; there are always associated risks with chemical control as shown below May be most effective where infestation is dense and must be killed before burning, may produce herbicide-resistant plants or harm flora and fauna

 

Control Warnings:

Disposal - Make sure to properly discard all plant pieces in thick plastic bags and transport them to a sanitary landfill site or incinerator. Composting is not an appropriate means of disposal as this may result in further distribution. Remember that humans can actually spread invasive plants by taking seeds from one place to another on clothing, tires, equipment, etc.

Chemicals - Although some chemicals are approved for control of invasive plants, extreme caution must be taken as many pesticides are harmful to humans. Permits may be required for chemical use and buffer zones exist beside waterways to protect fish and wildlife. Chemical control is not a long-term solution and therefore should be part of a finite plan and applied sparingly. Please see the following web sites for further information: Provincial: MWLAP Pest Information  Federal: Pest Management Regulatory Agency

Biological - Extreme caution must be taken when introducing one organism to control another. Intensive testing must occur before initiating a safe and effective biological control agent. Please contact local government or environmental agencies to determine available volunteer opportunities.

 

Additional Resources