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BMP: ENGLISH IVY (Hedera helix)

Common names:

English Ivy

Atlantic ivy or Irish ivy

Scientific Name:

Hedera helix (syns. Hedera helix ssp. helix, Hedera canariensis, Hedera helix ssp. canariensis)

Hedera hibernica (syns. Hedera helix ssp. hibernica)

Noxious Weed Listing:

Description:

General:

English ivy is an evergreen climbing vine in the Araliaceae (Ginseng) family.  It has historically been a common garden ornamental and has more than 400 cultivars.  It has escaped cultivation to become highly invasive in forests and natural areas throughout the Pacific Northwest.  Native to Europe, these plants are characterized by long viny stems reaching up to 30 m in length, with aerial, clinging small roots. English ivy damages desirable vegetation by shading out and smothering plants.  English ivy also covers trees making them more susceptible to wind damage due to the additional weight of the ivy in the trees as well as the additional drag of the evergreen leafy vines.  English ivy has two distinct growth forms: a juvenile form, that is characterized by rapid clonal and vegetative growth, and a mature form characterized by flowering and berry production.

In Oregon, three Hedera species have been documented: English ivy (H. helix), Atlantic ivy (H. hibernica), and Persian ivy (H. colchica). However, only H. helix and H. hibernica are listed as noxious weeds in Oregon. The invasive plant commonly referred to as English ivy is actually comprised of both H. helix and H. hibernica. Identification and differentiation between the species are complicated because of there many cultivated varieties. Both H. helix and H. hibernica have been commonly sold as English ivy, but can be differentiated by leaf shape and tiny hairs on the young leaves. These two species can also be differentiated through genetic testing.

Leaves:

The leaves come in two forms: juvenile and mature.  Both leaves are evergreen, leathery, and palmately shaped. Juvenile leaves have 3-5 lobes and are slightly hairy.  Generally, the lobes on H. helix are deeper than H. hibernica, but the lobes can vary. The leaves of mature ivy are ovate to diamond-shaped, unlobed or slightly lobed, darker green and more leathery. On both growth forms, the leaves alternate along the vines and are up to 10 cm long. Leaves can be toxic to humans and cattle if ingested.  Leaves can also cause contact dermatitis in sensitive individuals.

Flowers

English ivy generally will only flower under conditions with adequate light and optimal nutrients.  Flowers are only produced high in the tree canopy within infested forests, or along steep slopes.  English ivy flowers in the fall and are pollinated by insects.  Adult plants flower in clusters. The flowers are five-petaled, greenish to white in coloration and are only 3-5 mm long.

Fruits

Fruits develop as fleshy, dark blue to black berries that ripen in spring.  Thousands of fruits can be produced by an adult plant each year.  English ivy berries, particularly when underdeveloped, can be toxic to humans and cattle if ingested. These fruits are 5-10 mm in size and hold 1-3 seeds. Approximately 70% of the seeds produced are viable.

Roots

The juvenile English ivy plants have adventitious roots at their nodes.  Roots are generally shallowly rooted, but robust.  English ivy also forms aerial, clinging rootlets, allowing it to adhere and climb vertically.  Adult English ivy plants form a woody base.

Reproduction:

English ivy reproduces both from mature seeds as well as from root-like stems and sprouting fragments.  The berries of English ivy are ingested by birds and the seeds can be dispersed great distances from parent plants. New plants can regenerate from stems and fragments from both the mature and juvenile growth forms. Regenerating plants maintain the growth form of their parents, such that plants formed from stem regeneration of adult form plants will keep adult characteristics.  Once established juvenile plants can live up to 10 years before reaching maturation.   English ivy plants can live up to 100 years or longer with one plant in England being documented at more than 400 years in age.

Habitat:

The areas most infested by English ivy are urban natural areas, disturbed forests, woodlands, and along stream corridors.  Plants grown in moist soils with summer shade and winter sunlight will flourish.  Urban forest and natural areas are especially impacted as a result of repeated reinfestation from garden escapees.

Impacts:

  • Weighs down and harms large canopy trees making them more susceptible to wind throw
  • Smothers and displaces forest floor vegetation.
  • Degrades wildlife habit and reduces the diversity of animals in infested areas.
  • Toxic berries and leaves can cause injury.
  • Very invasive with rapid and intense vegetative growth, that can quickly transform a site.
  • Seeds disperse great distances, making containment of infestations very difficult.
  • Can be a reservoir for bacterial leaf scorch harmful to elms, oaks, and maples.
  • Vines tangle among native understory making removal difficult.
  • Increases erosion due to the displacement of native species and a shallow root system.

Introduction:

The original introduction of English ivy to the United States is believed to have been by European immigrants during colonial times as a garden ornamental. The earliest record of English ivy in North America dates to 1727.  Introduction to the Portland area occurred between 1875 and 1899 (Christy et al., 2009).

Distribution:

Clackamas County:

English ivy can be found throughout Clackamas County.  It is very widespread and directly impacts properties throughout the county.  As a ubiquitous weed, this is not a species that is actively surveyed and the mapped distributions do not represent the full extent of the English ivy population in Clackamas County.

State of Oregon:

United States:

Management:

Strategy:

The management of invasive weeds is best served through a process known as Integrated Pest Management (IPM).  IPM is a weed management methodology that utilizes:

  • Management thresholds to determine when and if to initiate control,
  • The ecology and life history characteristics of the targeted invasive weed,
  • Site-specific conditions and land use considerations to inform management practices,
  • The effectiveness and efficiency of various control methods.

An IPM based strategy ensures the maximum effectiveness of treatment measures.  IPM strategies typically use more than one management method to target one or more susceptible life stages.  It should be adaptive to site conditions in the field and to the response of a plant to management.  The utilization of multiple management tools inherently reduces the use of herbicides in a management plan.  The IPM process ultimately provides a framework for the establishment of Best Management Practices (BMP) which outlines the best approach for controlling a weed particular infestation.

Manual:

English ivy is often best controlled using manual control methods.  The waxy leaves of English ivy and its ability to regenerate from stems and fragments, make it resistant to chemical and mechanical control methods.  While effective the removal of English ivy can be time-consuming and labor-intensive.  As such, persistence is possibly the most important factor in determining the success of your treatments.  It has been suggested that an acre of English ivy dominated forest requires more than 300 man-hours for an initial clearing and continued maintenance to restore a site. So restoration efforts should plant their work accordingly

The first step is to choose an area, that can receive repeated control efforts.  Prioritize your site.  Choose a portion of your management area that is of highest priority, or work from a relatively intact area, and slowly expand your treatments systematically outward.  Look at the concentration and location of the ivy, the landscape, soil moisture, abundance of native plants in the area as well as the number and skill of workers assisting.  Before handling English ivy be sure to wear long sleeves, long pants, and gloves to protect yourself from potential dermatitis.  Utilize tools such as shovels, rakes, mattocks, and weed wrenches to assist in the removal of the roots.  Saws, loppers, and hand clippers can be used to cut vines.

In locations where native plants are abundant, the preferred practice is hand removal.  Vines growing on trees should be targeted first to prevent flowering and seed set and to preserve canopy trees on site.  Vines on trees should be cut using a saw, loppers or hand clippers around the entire base of the tree and also at a comfortable arm reach then removed from the tree. Leave the remaining ivy above the cut line to dry out and fall down on its own.  All ivy should be removed within, a minimum of 3 feet around the trunk to better protect the tree.  Flowering or seeding plants should be removed to prevent seeding or regeneration.  For ground ivy control should focus on one location, pulling every vine and root up within reaching distance, before moving to a new location.  Working systematically from a core area.   Manual control of English ivy is best done in the fall and winter when the ground is soft and plants are not seeding.

When few native plants reside on the property and there are sufficient workers, English ivy can be removed in large mats using a technique called the ‘Log Roll’.  This technique relies upon first defining a treatment area.  The perimeter of the area is cut and a line of workers pull the edge of the mat, rolling vines and roots of the ivy on top of itself. It is important to shake the roots to remove soil.  The roll should then be mulched in place to prevent resprouting.  Workers should also follow up in the cleared site to remove any missed roots. This practice can be done on both flat ground and on hillsides. Soils with higher water content allow for an easier pull.

Additional tips to reduce erosion and minimize damage to native plants:

  • Remove as much of the root system as possible by pulling the vine directly where the root comes out of the ground
  • Minimize trampling and churning of the soil
  • Protect native plants that are present through careful and conscientious pulling and walking
  • Be thorough, by completely clearing an area before moving on

Mechanical:

English ivy can be mowed or cut but this is generally not recommended due to its ability to regenerate following cutting.

Cultural:

Grazing has been used to defoliate large infestations of English ivy.  Goats and sheep will graze the ivy leaves, but plants will readily resprout following grazing.  As such, grazing animals must be rotated repeatedly back onsite to suppress regrowth.  English ivy is generally not favored by grazing animals, so co-occurring native plants are usually grazed more strongly than the ivy itself.  As such, grazing is generally considered to be ineffective, or of limited use.  Mature ivy plants are also generally found growing above the browse line, so manual removal of tree ivy is required in conjunction with any grazing strategy.

English ivy is fire resistant and doesn’t carry a fire well.    The repeated torching of ivy plants will cause cellular damage and dieback.  With persistence, this method will exhaust nutrients as the English ivy resprouts, but it is generally inefficient compared to other methods.  As such this method is generally not recommended.

Chemical:

 

Effective chemical control of English ivy is dependent on a few variables including timing, sensible application, and the proper mixture of chemicals. The timing is important to limit damage to native plants. Herbicide application during dry and sunny periods in late winter can be an effective chemical control on English ivy. The ivy is still alive and may still be growing in the winter while most native plants are dormant and protected.  Herbicide has shown to be successful when applied directly to cut stems specifically around a tree trunk.

Foliar application of herbicides is deterred by the waxy coating on the leaves. This is especially true for older/mature leaves and application during the growing season.  This leads to runoff of herbicide onto nearby native plants.  A fatty acid can be applied before or with the herbicide application to increase absorption into the leaves.

Widespread chemical control of English ivy is not suggested and should only to be considered in areas completely dominated by ivy or on difficult sites were manual control methods may be impractical or dangerous.

Before you Start:

  • Before purchasing any herbicide product it is important to read the label.  The label is the Law.  Carefully review all parts of the label even if you have used the product before.  Select a product that is most appropriate for your site.  If you have questions, ask your vendor before purchasing a product.
  • When selecting herbicides always use a product appropriately labeled for your site. Follow label recommendations and restrictions at all times.  If any information provided here contradicts the label, the label takes precedence.  Always follow the label!
  • Protect yourself.  Always wear the recommended protective clothing identified on your label and shower after use.
  • When applying herbicides use spot spray techniques whenever possible to avoid harming non-target plants.
  • Do not apply during windy or breezy conditions that may result in drift to non-target plants
  • Avoid spraying near water.  Hand-pull in these areas, to protect aquatic and riparian plants and wildlife.
  • Avoid exposure to pets, pollinators, and wildlife.  Remove animals from treatment areas to avoid exposure to herbicides. Follow the reentry instructions on your herbicide label and keep pets out of the area until the herbicides have dried and it is safe to return.  Avoid spraying when insects and animals are active.  Avoid spraying blooming plants to minimize any effects on bees and other pollinators.
  • Be sure to store any chemicals out of the reach of children and pets to keep your family safe.
  • Product labels and formulations change regularly.  Check the Pacific Northwest Weed Management Handbook and the label for current control recommendations.

Herbicides:

The mention of any brand name product is not, and should not be construed as an endorsement for that product.  They are included here only for educational purposes.  Suggested rates are generalized by active ingredient.  Specific rates will vary between products.  Be sure to review the label before application and use the recommended label rate at all times.

Active Ingredients

Product Names: Accord, Aquamaster, Rodeo, Roundup, and various others

Rate:
Spot treat: use 2% to 5% v/v solution in water, with a non-ionic surfactant
Low volume/thin line: 10% v/v solutions in water.
Cut stump: 25% v/v solutions in water.

Time: Apply when actively growing in late summer early fall.  An application can also be made on sunny winter days to avoid harming co-occurring natives. Cut stump applications should be made directly after cutting and during the dormant season for best results.

Comments: Wait four months after foliar treatment before cutting again. For cut stump application, cut stems horizontally or at ground level. Apply the solution directly after the cut. Treatment controls most resprouts. Glyphosate is not selective and will harm grasses.  Use care when working around desirable plants to avoid damage.  Leaves should be sprayed until wet but not dripping to achieve good control.

Product Names: Garlon 3A, Garlon 4 Ultra (triclopyr ester), Pathfinder II

Rate:
Spot treat: 2 to 5% v/v solution in water with a non-ionic surfactant.
Low volume/thin line: 10% v/v solution plus 20% basal oil concentrate in water.
Cut stump: 20% v/v solution in water.

Time: Apply post emergence in late summer to early fall, (August – October) when plants are growing rapidly. Cut stump applications should be made directly after a cut and during the dormant season for best results.

Comments: For cut stem treatment, follow the application description in Glyphosate. Triclopyr is selective and will harm desirable broad-leaf plants, trees, and shrubs.  Use care when working around desirable plants to avoid damage.  Leaves should be sprayed until wet but not dripping to achieve good control.  Triclopyr ester formulations may volatilize under warm temperatures.

Product Names: Tordon 22K

Rate:
Broadcast:  3-4 pints/acre (0.75 to 1 lb a.e/acre) plus .25 to .5% v/v surfactant

Time: Apply postemergence in late summer to early fall, (August – October) when plants are growing rapidly at or beyond early to full bloom stage.

Comments: Picloram can have long-term soil activity and has shown to move with groundwater.  It should not be used around trees because of root uptake.  Use care when working around desirable plants to avoid damage.  Leaves should be sprayed until wet but not dripping to achieve good control. Restricted herbicide.

Product Names: Arsenal, Habitat, Stalker, Chopper, Polaris

Rate:
Spot treat: 1 to 2% v/v solution plus .25 to .5% surfactant v/v in water.
Low volume/thin line: 10% v/v solution plus 20% ethylated crop oil in water.
Cut stump: 20% v/v solution in water plus 20% ethylated crop oil in water.

Time: Apply post emergence in late summer to early fall when the plant is growing rapidly.

Comments: Imazapyr exhibits some residual effects in the soil and may result in bare ground around plants after treatment. Care should be taken when replanting.  Cut stump applications should be made directly after cutting and during the dormant season for best results.

Product Names: Tank Mixed

Rate:
Spot treat: 4% v/v Glyphosate solution + 2% v/v Triclopyr solution, with 1-2% non-ionic surfactant v/v in water.

Time: Apply in late summer with a late fall follow up.

Comments: Treat when temperatures are above 65 F when no rain is expected for 2-3 days.

Biological:

There are no effective biological control agents available for English ivy.

Disposal:

 

There are many ways to dispose of English ivy when clearing your property. For small infestations, bagging up pulled plants is the best practice if possible.  For larger infestations, pile up the debris and let it dry out.  Placing a tarp under the pile will help prevent resprouting.  Piles can also be covered to speed up drying and decompositions.  Large debris piles can create dead spots, so placement of piles should be placed to minimize the impact to desirable vegetation.  Under dry conditions, plants can be chopped into a mulch and spread over the area for ground cover and nutrients, but be careful with this method as covering the ground will reduce the visibility of missed/live roots.

 

Follow-Up:

Diligence is the most important aspect of controlling English Ivy.  Ivy plants will readily resprout from any roots left remaining, so repeated follow-up is required. An herbicide application in summer has shown to be the most effective after treatment. Re-treatment may be required to achieve effective control.  The seed may persist in the soil for years following treatment or arrive on-site from adjacent and nearby infestations.

Best Management Practices:

Monoculture Infestations:

  • Consider the land use practices on site.  Identify, any site-specific considerations that should be taken into account before initiating control.
  • Be sure you can properly identify English ivy.  If you are unsure about your weed bring a sample to the Conservation District, and we can help to identify your particular weed.
  • Identify any native or desirable plants nearby, and take precautions to minimize any negative impact on them.
  • Herbicide application is often the best approach with respect to cost, time, and erosion protection for large ivy infestations with few desirable plants.
  • Winter applications have shown to be effective while minimizing the impact to native, but spray only during when winter weather is above 55 F, and no precipitation is expected for at least three days.  Otherwise, plan treatments for late summer.
  • Follow-up treatments 6-12 months afterward can be as re-treatment of herbicide, spot spray herbicide application or spot manual removal.
  • Replant site with site-appropriate native vegetation as soon as possible. Grass seed can be spread to stabilize soil in between removal and plantings.
  • Continue to monitor the site for regrowth and treat any new infestations.

Small Infestations within native or desirable vegetation:

  • Consider the land use practices on site.  Identify, any site-specific considerations that should be taken into account before initiating control.
  • Be sure you can properly identify English ivy.  If you are unsure about your weed bring a sample to the Conservation District, and we can help to identify your particular weed.
  • Identify any native or desirable plants nearby, and take precautions to minimize any negative impact on them.
  • A manual approach is best with a limited spot spray application of herbicide in dense patches within native vegetation.
  • Pull plants in winter and spring when the soil is moist and the ivy is prominent.
  • Replanting is not as necessary in small infestations within native vegetation because the natives will expand into open areas. If large gaps are present, additional plantings may be beneficial.
  • Continue to monitor the site for regrowth and treat any new infestations as they occur.

Fun Facts:

  • Juvenile plants can climb as much as 30 ft per year.
  • Leaves and berries have been eaten as an expectorant.
  • A leaf reduction can be used to restore dark fabrics or dye hair and twigs can create yellow and brown dye.
  • Medicinally used since ancient times to treat rheumatism, toothache, bronchitis, and many skin problems including burns, infections, and cellulite.
  • Ivy has been long used in England as decorations during the Christmas season.

Gallery:

English ivy
Tree ivy infestation
English Ivy
English ivy flowers
English ivy berries
English Ivy seedling
English ivy in trees
Massive English Ivy Stem
English ivy after treatment

Additional Information:

References:

  1. Bossard, C. C., J. M. Randall, & M.C. Hoshovsky.  2000.  Invasive Plants of California’s Wildlands.  Berkeley, CA: University of California Press.  pp 277-281.
  2. Christy, J. A., A. Kimpo, V. Marttala, P. K. Gaddis, & N. L. Christy.  2009.  Urbanizing Flora of Portland Oregon 1806-2008.  Native Plant Society of Oregon Occasional Paper 3 pg. 218.
  3. DiTomaso, J.M. & E.A. Healy.  2007.  Weeds of California and Other Western State vol 2.  University of California ANR.  pp 1426-1434.
  4. DiTomaso, J.M., G.B. Kyser, S.R. Oneto, R. G. Wilson, S. B. Orloff, L. W. Anderson, S. D. Wright, J.A. Roncoroni, T.L. Miller, T.S. Prather.  2013.  Weed Control in Natural Areas in the Western United States.  Davis, CA: UC Weed Research and Information Center.  pp 341-343.
  5. Holloran, P., A. Mackenzie, S Farrell, D. Johnson.  2004.  The Weed Workers Handbook: A Guide to Techniques for Removing Bay Area Invasive Plants.  Berkeley, CA: California Invasive Plant Council.  pp 60-61
  6. Kaufman, S. R. & W. Kaufman.  2007.  Invasive Plants: Guide to identification and the Impacts and Control of Common North American Species.  Mechanicsburg, PA: Stackpole Books. pp 145-151
  7. King County Noxious Weed Control Program.  2011.  English ivy identification (Hedera helix).  https://www.kingcounty.gov/environment/animalsAndPlants/noxious-weeds/weed-identification/english-ivy.aspx  (Retrieved Jan 21, 2014).
  8. Oregon Flora Project. 2013.  Oregon Plant Atlas: Hedera helix.  http://www.oregonflora.org/atlas.php.  (Retrieved Jan 21, 2014)
  9. Peachy, E., D. Ball, A. Hulting, T. Miller, D. Morishita, P. Hutchinson. eds.  2013.  Pacific Northwest Weed Management Handbook: Control of Problem Weeds.  (Retrieved Jany 21, 2014).
  10. Soll, J. 2004.  Controlling English Ivy (Hedera helix) in the Pacific Northwest. The Nature Conservancy.  https://www.invasive.org/gist/moredocs/hedhel02.pdf   (Retrieved Jan 21, 2014)

BMP: SCOTCH BROOM (Cytisus scoparius)

Common name:

Scotch broom, Scot’s broom, English broom

Scientific Name:

Cytisus scoparius (syns. Sarothamnus scoparius, Spartium scoparium)

Noxious Weed Listing:

Description:

General:

Scotch broom is a fast growing shrub in the Fabaceae (pea) family, characterized by its masses of yellow flowers.  It grows upright on young, green, 5-angled stems which are hairy.  Broom forms dense stands and is shade intolerant.  Mature plants can reach 10 feet in height although most plants are typically 3-5 feet tall. Scotch broom is a deciduous nitrogen-fixing plant. Scotch broom is an invasive plant found in low elevations from British Columbia to California.

Leaves:

The leaves of Scotch broom are alternate and compound consisting of three oblong leaflets.  Very few leaves on stems. New twigs may only have one leaflet. Leaflets are small 5-20 mm long.  The leaflets are dark green and fleshy and serrated along their margin.  The underside of the leaflets are covered by flattened, short hairs while the upper surface is smooth.

Flowers

The flowers are pea-like; upper and lower curved petal have wing petals on each side. Scotch broom flowers are yellow to partially to complete red in color. Small, only 1-2.5 cm. The stamens are fused.  Plants flower from April to June.

Fruits

Fruits develop as seed pods that mature in June-July. Seed pods are flat, 2-5 cm long, smooth with long silky hairs which turn dark brown to black when mature. Seeds are small 2mm, long and shiny, brown to black in color with a whitish appendage (fatty deposit) which attracts ants and some birds.  3-12 seeds found within each pod.

Roots

The Scotch broom plants form deep, branched taproots with fine roots associated with nitrogen fixation. New shoots can grow from the crown when plants are cut above the crown.

Reproduction:

Scotch broom reproduces by seed.  Seeds are dispersed when pods dry, split in half and twist. This action can send seeds up to 3 meters but is often just a short distance from the plant.  A variety of ants are attracted to the white seed appendages and disperse the seeds further. Seeds have a hard coating which allows them to survive up to 30 years in the field. Scotch broom produces seed at 2 or 3 years but is in full reproduction at 3-5 years lasting until year 9. Up to 3500 pods can be produced from one adult shrub.  Scotch broom lives for 15-20 years.

Habitat:

The areas most infested by Scotch broom are disturbed sites,  grasslands, open forests, and riparian corridors. The plant likes coastal areas and low elevations in dry conditions with plenty of sunshine. Scotch broom flourishes in infertile soil because it is a nitrogen-fixing plant which allows it to grow where many plants fail to flourish.  Scotch broom likes sandy, acidic and dry soil.

Impacts:

  • Grows rapidly and forms dense stands.
  • Out-competes native plants by shading out and by changing soil fertility.
  • Prevents reforestation by out-competing conifer seedlings.
  • Dramatically increases the hazard and intensity of fires
  • Displaces native plants and wildlife.

Introduction:

The original introduction of Scotch broom to Oregon is believed to have occurred between 1875 and 1899 (Christy et al., 2009). The plant is native to Europe and North Africa and was commonly introduced by European settlers to remind them of their home but quickly escaped cultivation. It was also used to stabilize soil, especially along roadways before the realization of its invasive characteristics. Due to its showy flowers, Scotch broom was commonly produced in the horticultural trade where many varieties have been developed.

Distribution:

Clackamas County:

Scotch broom can be found throughout Clackamas County.  It is very widespread and directly impacts properties throughout the county.  As a ubiquitous weed, this is not a species that is actively surveyed and the mapped distributions do not represent the full extent of the Scotch broom population in Clackamas County.

State of Oregon:

United States:

Management:

Strategy:

The management of invasive weeds is best served through a process known as Integrated Pest Management (IPM).  IPM is a weed management methodology that utilizes:

  • Management thresholds to determine when and if to initiate control,
  • The ecology and life history characteristics of the targeted invasive weed,
  • Site-specific conditions and land use considerations to inform management practices,
  • The effectiveness and efficiency of various control methods.

An IPM based strategy ensures the maximum effectiveness of treatment measures.  IPM strategies typically use more than one management method to target one or more susceptible life stages.  It is adaptive to site conditions in the field and to the response of a plant to management.  The utilization of multiple management tools also inherently reduces the use of herbicides in a management plan.   The IPM process ultimately provides a framework for the establishment of Best Management Practices (BMP) which outlines the best approach for controlling a weed particular infestation.

Manual:

The control of Scotch broom can be a difficult task.  The long-lived seeds, long growing season, aggressive roots, thick stands and the ability to resprout from young stumps or root crowns make Scotch broom difficult to control.

Manual removal of Scotch broom can be an effective control option especially for smaller infestations, but it is labor intensive.  Seedling and small shrubs can be hand pulled between January and May. Pulling when the soil is moist will make it easier to remove the roots and put less strain on the worker. All plants and roots need to be removed to reduce regrowth. Continual manual removal, every year pulling the next generation, is one of the most effective controls for Scotch broom. A weed wrench, shovel or hoe can be used to assist with root removal.

While manual removal can be an effective treatment, it can cause heavy soil disturbances on site. Soil disturbance can bring broom seeds deep in the soil to the surface creating a new generation of growth.

For old established stands, cut Scotch broom between ground level and three inches using loppers or a saw during the dry season (July to August). Try to cut before seed pods mature to limit spread.

Cutting alone during the right time can be a useful management tool to prevent seeding.  Young Scotch broom plants will resprout following cutting from above the root crowns.  Older plants generally will not resprout following a cutting.  Large stands of resprouting plants following cutting are best controlled with a targeted herbicide application.

Mechanical:

Large infestations of Scotch broom can be removed through mowing.  Like cutting, brush mowing alone won’t kill the broom.  Mowing should be done between flowering and seed maturity and must be repeated at regular intervals to exhaust plant.  Mowing is not a very effective control by itself, however, when used in conjunction with herbicide application it can be very effective.
Mowing equipment can transport seeds if not cleaned before leaving a site and if plants are cut during seed production.

Cultural:

Burning can be an effective tool to remove debris, but it will not eliminate Scotch broom.  Other management such as crown removal or herbicide application is required to achieve control.  The available fuels in dense broom stands can also be substantial, so care needs to be taken to keep a fire contained.  As such fire is generally not a recommended control measure.  You should check with your local Fire District or the Oregon Department of Forestry for rules and recommendations.

Grazing by goats is a potential method for controlling Scotch broom.  Unfortunately, broom plants can be toxic to both humans and livestock which limits other grazing activity. Goats confined to a small area will eat the resprouting Scotch broom after treatment.

Chemical:

Chemical control is an effective tool to control large stands of Scotch broom.  Continued treatment and monitoring will be required due to the copious number of seedlings emerging from the seed bank.    Scotch broom is susceptible to several systemic herbicides. Plants should not be mowed or cut after application for a minimum of two weeks to allow the herbicide to reach the roots. Scotch broom flowers can hinder herbicide application by not allowing the chemical to reach other areas of the plant. Large treated/dead stands of brooms are a fire hazard and need to be monitored and removed if necessary.

Before you Start:

  • Before purchasing any herbicide product it is important to read the label.  The label is the Law.  Carefully review all parts of the label even if you have used the product before.  Select a product that is most appropriate for your site.  If you have questions, ask your vendor before purchasing a product.
  • When selecting herbicides always use a product appropriately labeled for your site. Follow label recommendations and restrictions at all times.  If any information provided here contradicts the label, the label takes precedence.  Always follow the label!
  • Protect yourself.  Always wear the recommended protective clothing identified on your label and shower after use.
  • When applying herbicides use spot spray techniques whenever possible to avoid harming non-target plants.
  • Do not apply during windy or breezy conditions that may result in drift to non-target plants
  • Avoid spraying near water.  Hand-pull in these areas, to protect aquatic and riparian plants and wildlife.
  • Avoid exposure to pets, pollinators, and wildlife.  Remove animals from treatment areas to avoid exposure to herbicides. Follow the reentry instructions on your herbicide label and keep pets out of the area until the herbicides have dried.  Avoid spraying when insects and animals are active.  Avoid spraying blooming plants to minimize any effects to bees and pollinators.
  • Be sure to store any chemicals, out of the reach of children and pets to keep your family safe.
  • Product labels and formulations change regularly.  Check the Pacific Northwest Weed Management Handbook and the label for current control recommendations.

Herbicides:

The mention of any brand name product is not, and should not be construed as an endorsement for that product.  They are included here only for educational purposes.  Suggested rates are generalized by active ingredient.  Specific rates will vary between products.  Be sure to review the label before application and use the recommended label rate at all times.

Active Ingredients

Product Names: Accord, Aquamaster, Rodeo, Roundup, XRT II, and various others

Rate:
Spot treat: use 1.5% to 2% v/v solutions.
Cut stump: 25% v/v (up to 50% can reduce resprouting)

Time: Foliar application in late summer or early fall. Cut stump application again in late summer to early fall, immediately after cutting.

Comments: Re-treatment may be required to achieve effective control.  Glyphosate is not selective and will harm grasses.  Use care when working around desirable plants to avoid damage.  Leaves should be sprayed until wet but not dripping to achieve good control. Cut stems horizontally at or near ground level and immediately apply herbicide.

Product Names: Garlon 4 (triclopyr ester),  Garlon 3A, Element 3A (triclopyr amine), Pathfinder II

Rate:
Broadcast: Triclopyr ester- 2 – 3 qts/acre (1 – 1.5 at ae/acre), Triclopyr amine- 3 – 4 qts/acre (1.125 – 1.5 qt ae/acre)
Spot treat: Triclopyr ester use 0.75% to 1% v/v solution, Triclopyr amine use 1% – 1.5% v/v solution plus 0.25% – 0.5%  v/v surfactant
Basal Bark: Triclopyr ester- use 20% v/v solution ethylated crop oil and water
Cut stump: Triclopyr amine-50% in water

Time: Apply post emergence when plants are growing rapidly in the spring and again in the fall. Applications should be made before a killing frost.

Comments: Re-treatment may be required to achieve effective control.  Triclopyr is selective and will not harm grasses but will harm desirable broadleaf plants, trees, and shrubs.  Use care when working around desirable plants to avoid damage.  Leaves should be sprayed until wet but not dripping to achieve good control.  Triclopyr ester formulations may volatilize under warm temperatures.

Product Names: Crossbow (Triclopyr + 2, 4D)

Rate:
Spot treat: 0.5% to 1.5% v/v solution

Time: Apply post emergence when plants are growing rapidly in the spring and again in the fall. Applications should be made before a killing frost.

Comments: Re-treatment may be required to achieve effective control.  Triclopyr + 2, 4D is selective and will not harm grasses, but may damage desirable broadleaf plants, trees, and shrubs.  Use care when working around desirable plants to avoid damage.  Leaves should be sprayed until wet but not dripping to achieve good control.  Check the label for specific warnings and recommendations.

Product Names: Arsenal, Habitat, Stalker, Chopper, Polaris

Rate:
Spot treat: 1 to 2% v/v solution plus 0.25 to 0.5% surfactant v/v
Cut stump: 20% v/v solution in water plus 20% ethylated crop oil
Basal bark: 20% v/v solution in water plus 20% ethylated crop oil

Time: Apply post emergence in late summer to early fall when the plant is growing rapidly. Best when used in late summer to early fall.

Comments: Imazapyr is a soil residual herbicide and may result in bare ground around plants after treatment.

Product Names: Tordon 22K

Rate:
Broadcast:  2 pints/acre (non-cropland)  or 1 qt/acre (rangeland) plus 0.25 to 0.5% v/v surfactant

Time: Apply post emergence in spring and again in fall when plants are growing rapidly at or beyond early to full bloom stage.

Comments: Picloram can cause long-term soil activity and should not be used around trees because of root uptake.  Use care when working around desirable plants to avoid damage.  Leaves should be sprayed until wet but not dripping to achieve good control. Restricted herbicide: not registered in California.

Biological:

There are several insects which feed on the seeds and leaves of Scotch broom.  Scotch broom bruchid (Bruchidius villosus), Scotch broom seed weevils (Exapion fuscirostre or Aprion fuscirostre), twig mining moth (Leucoptera sartifolilella), Eriophyid gall mite (Aceria genistae) and the shoot tip leaf moth (Agonopterix nervosa) are known to damage the Scotch broom plants. These bugs will not eradicate an infestation, they have poor to fair effectiveness controlling a stand and any results might not be seen for up to 7 years.

Disposal:

Scotch broom plants that have not gone to seed are able to be disposed of in regular household trash cans or in yard debris containers. Cut plants can be left on site but can be a fire hazard. Scotch broom plants that have gone to seed should be left on site to minimize the spread of the seeds, or piled on tarps and bagged before being moved off-site. Plant debris can also be burned on site with appropriate safety measures and permits. You should check with your local Fire District or the Oregon Department of Forestry for rules and recommendations.

Follow-Up:

Diligence is the most important aspect for controlling Scotch broom.  New broom plants will germinate from the seed bank living in the soil even after years following treatments and soil disturbances, so repeated follow-up is required.

Best Management Practices:

Small Infestations:

  • Consider the land use practices on site.  Identify, any site-specific considerations that should be taken into account before initiating control.
  • Be sure you can properly identify Scotch broom.  If you are unsure about your weed bring a sample to the Conservation District, and we can help to identify your particular weed.
  • Identify any native or desirable plants nearby, and take precautions to minimize any negative impact on them.
  • Manual removal is very effective at controlling small infestations of Scotch broom (plants under 1″).  Plants can be pulled or dug up when the soil is moist (fall through spring).
  • Replace divots and holes created.
  • Spot spray herbicide appropriately.
  • Monitor the site for regrowth, and remove new sprouts as soon as they appear.
  • Do not leave soil bare, mulch or replant to stabilize soil and compete with broom regrowth.
  • Replant heavily infested areas to increase shade and suppress new seedlings.

Large Infestations:

  • Consider the land use practices on site.  Identify, any site-specific considerations that should be taken into account before initiating control.
  • Be sure you can properly identify Scotch broom.  If you are unsure about your weed bring a sample to the Conservation District, and we can help to identify your particular weed.
  • Identify any native or desirable plants nearby, and take precautions to minimize any negative impact on them.
  • Mow or cut down the Scotch broom using a brush mower or chainsaw to remove large well-established individuals.
  • Apply herbicides to cut stems to prevent regrowth.
  • Follow up with a broadcast or spot herbicide application to treat seedlings and resprouting plants.
  • Several applications over several years will be needed to suppress and eradicate Scotch broom infestations.
  • Continue to monitor the site for regrowth and treat any new infestations.
  • Replant heavily infested areas to increase shade and suppress new seedlings.

Fun Facts:

  • Scotch broom gets its name because the plant is historically used in Scotland to make brooms.
  • Photosynthesis occurs in the green stems and not in the leaves (like most plants).
  • Used to make cloth, coffee and as a diuretic.
  • Scotch broom contains chemicals (toxic alkaloids sparteine and isosparteine) that affects heart rhythm and one that might increase body water loss. (Unsafe to use medicinally)

Gallery:

Vegetative Scotch broom
large vegetated Scotch Broom Infestation
Scotch broom plant
Scotch broom flowers
Scotch broom bicolor flower
Scotch broom flowers and seed pods
Scotch broom seed pod
Scotch broom bruchid (Bruchidius villiosus) biological control
Scotch broom seed weevil biological control emerging from seed pod
Scotch broom seed weevil (Exapion fuscirostre) biological control
Scotch broom bruchid (Bruchidius villosus) biological control damage to seed
Scotch broom infestation

Additional Information:

References:

  1. Bossard, C. C., J. M. Randall, & M.C. Hoshovsky.  2000.  Invasive Plants of California’s Wildlands.  Berkeley, CA: University of California Press.  pp 277-281.
  2. Christy, J. A., A. Kimpo, V. Marttala, P. K. Gaddis, & N. L. Christy.  2009.  Urbanizing Flora of Portland Oregon 1806-2008.  Native Plant Society of Oregon Occasional Paper 3 pg. 218.
  3. DiTomaso, J.M. & E.A. Healy.  2007.  Weeds of California and Other Western State vol 2.  University of California ANR.  pp 1426-1434.
  4. DiTomaso, J.M., G.B. Kyser, S.R. Oneto, R. G. Wilson, S. B. Orloff, L. W. Anderson, S. D. Wright, J.A. Roncoroni, T.L. Miller, T.S. Prather.  2013.  Weed Control in Natural Areas in the Western United States.  Davis, CA: UC Weed Research and Information Center.  pp 341-343.
  5. Holloran, P., A. Mackenzie, S Farrell, D. Johnson.  2004.  The Weed Workers Handbook: A Guide to Techniques for Removing Bay Area Invasive Plants.  Berkeley, CA: California Invasive Plant Council.  pp 60-61
  6. Kaufman, S. R. & W. Kaufman.  2007.  Invasive Plants: Guide to identification and the Impacts and Control of Common North American Species.  Mechanicsburg, PA: Stackpole Books. pp 145-151
  7. King County Noxious Weed Control Program.  2011.  King County Best Management Practices for Controlling Scotch Broom, Scot’s Broom (Cytisus scoparius).  https://your.kingcounty.gov/dnrp/library/water-and-land/weeds/BMPs/Scotch-Broom-Control.pdf  (Retrieved Feb 25, 2016).
  8. Oregon Flora Project. 2013.  Oregon Plant Atlas: Scotch broom.  https://www.oregonflora.org/atlas.php.  (Retrieved Feb 25, 2016)
  9. Peachy, E., D. Ball, A. Hulting, T. Miller, D. Morishita, P. Hutchinson. eds.  2013.  Pacific Northwest Weed Management Handbook: Control of Problem Weeds.  (Retrieved Feb 25, 2016).
  10. Hoshovsky, M. 2001.  Element Stewardship Abstract for Cytisus scoparius and Genista monspessulanus Scotch Broom, French Broom.  The Nature Conservancy.  https://www.invasive.org/weedcd/pdfs/tncweeds/cytisco.pdf   (Retrieved Feb 25, 2016)

BMP: HIMALAYAN BLACKBERRY (Rubus armeniacus)

Common name:

Himalayan Blackberry, Armenian Blackberry

Scientific Name:

Rubus armeniacus (syns. Rubus bifrons, Rubus discolor, Rubus procerus)

Noxious Weed Listing:

Description:

General:

Himalayan blackberry is a tall semi-woody shrub, characterized by thorny stems and dark edible fruits.  It grows upright on open ground and will climb over and trail over other vegetation.  Mature plants can reach 15 feet in height. The canes of Himalayan blackberry can reach lengths of 40 feet and are typically green to deep red in color.  Himalayan blackberry forms dense, nearly impenetrable thickets.  In some instance, canes can reach densities of more than 500 canes per square yard.  The canes of Himalayan blackberry typically last only three years before dying off, so dense thickets are often dominated by old canes.

Leaves:

The leaves of Himalayan blackberry are palmate and compound consisting of three to five leaflets.  The leaflets are dark green and fleshy and serrated along their margin.  The underside of the leaves are white in appearance and are covered by minute hairs. A row of small thorns also grows along the underside of the central vein of the leaf.

Flowers

The flowers are five-petaled and are white to pink in coloration.  The stamens and ovaries are abundant.  Plants flower from April to August in our area.

Fruits

Fruits develop as green drupe-like berries that ripen into dark purple to black berries in summer.  The fruits are edible up to an inch in length and widely consumed by wildlife and foragers.

Roots

The Himalayan blackberry plants form enlarged root crowns with numerous buds that develop into new canes.  They also have lateral roots that can reach 30 feet in length and extend 2-3 feet deep.

Reproduction:

Himalayan blackberry reproduces both by seed and vegetatively.  The berries produced are favored by many bird and mammal species, and the seeds can be deposited great distances from parent plants.  Many of the seeds may remain dormant in the soil for several years after dispersal.  Once a plant becomes established, it spreads locally through expanding roots and rhizomes.  The canes of adult blackberry plants will also root at the nodes to form daughter plants along its margin.

Habitat:

The areas most infested by Himalayan blackberry are disturbed sites, fencelines, and along stream corridors.  Blackberry flourishes on open ground, and on unmanaged sites.  Plants grown in wet soils tend to be dense and more robust.  Due to the movement by birds, Himalayan blackberry also is commonly found under perching sites, such as along fence rows and under power lines.

Impacts:

  • Himalayan blackberry is a highly invasive plant that replaces native vegetation.
  • The canes of blackberry can build up substantial litter layer which may serve as fuels for wildfire.
  • The thorns of the blackberry plants can limit the access to a site by both animals and people.
  • While dense thickets can be useful to some wildlife species, the diversity of habitats is greatly diminished, thereby diminishing the usability of a site to only a few species.

Introduction:

The first herbarium record for Himalayan blackberry in Oregon was collected in Marion County in 1922 (Oregon Flora, 2013).  The original introduction of Himalayan blackberry to Oregon is believed to have occurred between 1875 and 1899 but was first noted in our area in 1903.  By 1920 it was considered widespread throughout the Willamette Valley (Christy et al., 2009).

Distribution:

Clackamas County:

Himalayan Blackberry can be found throughout Clackamas County.  It is very widespread and directly impacts properties throughout the county.  As a ubiquitous weed, this is not a species that is actively surveyed and the mapped distributions do not represent the full extent of the Himalayan blackberry population in Clackamas County.

State of Oregon:

United States:

Management:

Strategy:

The management of invasive weeds is best served through a process know as Integrated Pest Management (IPM).  IPM is a weed management methodology that utilizes:
  • Management thresholds to determine when and if to initiate control,
  • The ecology and life history characteristics of the targeted invasive weed,
  • Site-specific conditions and land use considerations to inform management practices,
  • The effectiveness and efficiency of various control methods.
An IPM based strategy ensures the maximum effectiveness of treatment measures.  IPM strategies typically use more than one management method to target one or more susceptible life stages.  It is adaptive to site conditions in the field and to the response of a plant to management.  The utilization of multiple management tools also inherently reduces the use of herbicides in a management plan.   The IPM process ultimately provides a framework for the establishment of Best Management Practices (BMP) which outlines the best approach for controlling a weed particular infestation.

Considerations:

Before implementing weed control activities on your property it is important to consider the potential impact of your planned treatment.  Take the time to consider how your planned treatment activities will impact:
  • Animals-Recognize that treatment activities can negatively impact animals.  Plan your weed treatments to provide corridors and refuge to animals whenever possible.  Make a plan for reconnecting wildlife to your area after treatment.
  • Birds - Survey your treatment area for bird species and avoid treatments during nesting periods (Feb-Aug) or when fruiting to minimize the impact on bird species.
  • Beneficial insects and pollinators - Avoid treatments when plants are blooming to minimize the impact on native pollinators.  Also, plan treatments during cooler weather when insects are less active.
  • Native plants- Target weeds during the times of the year when native plants are dormant to minimize the impact on native trees and shrubs.  Use targeted weed control practices to only target invasive weeds
  • Soil erosion- Recognize the potential for your site to erode.  Be especially aware if working on sloped sites, as these tend to be more highly erodible.  Weed control practices will routinely result in bare ground, so have a replanting strategy ready following treatment to maintain your soils.

Manual:

The control of Himalayan blackberry can be a difficult task.  The sharp thorns and dense thickets formed by Himalayan blackberry inhibit movement and complicate control efforts. Himalayan blackberry thorns easily penetrate woven fabrics, and thus, thick leather gloves, long shirts, and thick pants are recommended when working with blackberry. Manual removal of Himalayan blackberry can be an effective control option, but it is labor-intensive and often a difficult and painful process.  Small seedlings can be easily pulled with thick gloves, but mature plants are not easily removed.  The dense thickets formed by blackberry greatly limit access.  A site can be made more accessible for manual removal by using a long board or sheets of plywood to mash blackberry canes down to the ground. Plants can then be cut at ground level using loppers, machetes, or saws.  Once cut, root crowns and large lateral roots can be grubbed out using a Pulaski, a mattock, shovel, or Shrub Buster.  It is important to remove as much of the root mass as possible to prevent resprouting.  While effective, this process heavily disturbs soils and increases the erosion potential of a site.  Therefore, this is not recommended on steep or unstable soils. While manual removal can be an effective treatment, it requires diligence to be effective.  A site will need regular follow-up to remove resprouts and seedlings.  A large number of seeds can persist in the soil under dense stands, so expect repeated efforts, as you exhaust the seed left in the soil. Cutting alone can be a useful management tool to prevent seeding and to allow access to a site.  Unless repeated regularly and over several years, cutting alone will not eliminate blackberry.  Blackberry plants will readily resprout following cutting from below-ground root crowns.  Cutting is best used in combination with the removal of root crowns and large lateral roots, or a targeted herbicide application to prevent resprouting.

Mechanical:

Large infestations of Himalayan blackberry can be removed through brush-mowing.  Like cutting, brush mowing alone won't kill Himalayan blackberry.  Mowing must be repeated at regular intervals to exhaust carbohydrates stored in underground roots.  Due to the thick growth of blackberry, mechanical removal can be very effective at increasing the access of a site to allow for crown and root removal, herbicide application, and replanting. Tillage can also be effective for removing blackberry root crowns.  Crowns and canes should be raked up and removed following tillage to prevent resprouting.  Tillage causes extensive soil disturbance, so it is generally not recommended, unless a site is undergoing renovation.  Blackberry can resprout from small root fragments, so follow-up should be carried out to target regrowth.

Cultural:

Burning can be an effective tool to clear large dense stands, but it will not eliminate Himalayan blackberry.  Other management such as crown removal or herbicide application is required to achieve control.  The available fuels in dense blackberry thickets can also be substantial, so care needs to be taken to keep the fire contained.  As such fire is generally not a recommended control measure.  You should check with your local Fire District or the Oregon Department of Forestry for rules and recommendations. Grazing can be an effective method for controlling blackberry.  Unfortunately, grazing animals generally also target other plants as well, so their use is only recommended when blackberries are the dominant vegetation.  Browsing grazers such as goats and sheep are best for controlling blackberry.  These grazers feed best on new growth, and target the leaves, while the blackberry canes remain relatively undisturbed.  Due to the grazing habits of browsing grazers, dense blackberry stands are best controlled by "flash grazing" a site with a large number of animals in a small area for a short period of time.

Chemical:

Due to the difficulties associated with controlling Himalayan blackberry, herbicides are often a component in the management of this species.  Himalayan blackberry is susceptible to several systemic herbicides.  Young canes are most susceptible, but should only be targeted after reaching at least 3 feet in height to allow the herbicide to be drawn down into its root system.  Plants should not be cut or removed for at least two weeks following an herbicide application.

Before you Start:

  • Before purchasing any herbicide product it is important to read the label.  The label is the Law.  Carefully review all parts of the label even if you have used the product before.  Select a product that is most appropriate for your site.  If you have questions, ask your vendor before purchasing a product.
  • When selecting herbicides always use a product appropriately labeled for your site. Follow label recommendations and restrictions at all times.  If any information provided here contradicts the label, the label takes precedence.  Always follow the label!
  • Protect yourself.  Always wear the recommended protective clothing identified on your label and shower after use.
  • When applying herbicides use spot spray techniques whenever possible to avoid harming non-target plants.
  • Do not apply during windy or breezy conditions that may result in drift to non-target plants
  • Avoid spraying near water.  Hand-pull in these areas, to protect aquatic and riparian plants and wildlife.
  • Avoid exposure to pets, pollinators, and wildlife.  Remove animals from treatment areas to avoid exposure to herbicides. Follow the reentry instructions on your herbicide label and keep pets out of the area until the herbicides have dried.  Avoid spraying when insects and animals are active.  Avoid spraying blooming plants to minimize any effects on bees and pollinators.
  • Be sure to store any chemicals, out of the reach of children and pets to keep your family safe.
  • Product labels and formulations change regularly.  Check the Pacific Northwest Weed Management Handbook and the label for current control recommendations.

Herbicides:

The mention of any brand name product is not, and should not be construed as an endorsement for that product.  They are included here only for educational purposes.  Suggested rates are generalized by active ingredient.  Specific rates will vary between products.  Be sure to review the label before application and use the recommended label rate at all times.
 

Active Ingredients

Product Names: Accord, Aquamaster, Rodeo, Roundup, and various others Rate: Broadcast: 2 - 3 qt per acre (2.25 to 3.4 lb ae/acre) Spot treat: use 0.5% to 1.5% v/v solutions. Time: Apply postemergence in late summer to early fall, (August - October) after canes and leaf canopy has reached maturity. Applications should be made before a killing frost. Comments: Re-treatment may be required to achieve effective control.  Glyphosate is not selective and will harm grasses as well as broadleaf plants.  Use care when working around desirable plants to avoid damage.  Leaves should be sprayed until wet but not dripping to achieve good control.
Product Names: Garlon 4 (triclopyr ester),  Garlon 3A, Element 3A (triclopyr amine), Vastlan (triclopyr choline) Rate: Broadcast: Triclopyr ester- 1-4 lb ae/acre, Triclopyr amine- 1.5-4.5 lb ae/acre, Triclopyr choline- 2-4 lb ae/acre. Spot treat: Triclopyr ester use 0.75% to 1% v/v solution, Triclopyr amine use 1% v/v solution. Basal Bark: Triclopyr ester- use 20% v/v solution with basal oil or seed oil. Time: Apply postemergence in late summer to early fall, (August - October) after canes and leaf canopy has reached maturity. Applications should be made before a killing frost. Comments: Re-treatment may be required to achieve effective control.  Triclopyr is selective and will harm desirable broadleaf plants, trees, and shrubs.  Use care when working around desirable plants to avoid damage.  Leaves should be sprayed until wet but not dripping to achieve good control.  Triclopyr ester formulations may volatilize under warm temperatures.
Product Names: Crossbow (Triclopyr + 2, 4D), Capstone (Triclopyr + aminopyralid) Rate: Broadcast: Triclopyr + 2, 4D- 1.5 gallons/acre, Triclopyr + aminopyralid- 6-9 pints/acre. Spot treat:  Triclopyr + 2, 4D- 1.0% to 1.5% v/v solution, Triclopyr + aminopyralid- equivalent to 6-9 pints/acre. Time: Apply postemergence in late summer to early fall, (August - October) after canes and leaf canopy has reached maturity. Applications should be made before a killing frost. Comments: Re-treatment may be required to achieve effective control.  Triclopyr + 2, 4D and Ticlopyr + aminopyralid are selective and will not harm grasses, but may damage desirable broadleaf plants, trees, and shrubs.  Use care when working around desirable plants to avoid damage.  Leaves should be sprayed until wet but not dripping to achieve good control.  Forage and manure derived from areas treated with Ticlopyr + aminopyralid, should not be composted or used around desirable vegetation. Check the label for specific warnings and recommendations.
Product Names: Escort Rate:0.5 to 1 oz product/acre (0.3 to 0.6 oz ai/acre) Time: Apply postemergence in late summer when fully leafed out, but before leaf discoloration. Comments: Metsulfuron is primarily active against broadleaf plants and generally will not harm grasses.

Biological:

Blackberry leaf rust fungus (Phragmidium violaceum) is an accidentally introduced European species that can result in defoliation of Himalayan blackberry.  It is not an approved biological control agent.  Infected plants should not be transported due to the potential impact of this species on agriculturally important species.

Disposal:

Small amounts of plant material can be disposed with yard debris, or composted on site.  Avoid composting plants that are seeding.  Seeds may persist in home composting systems and may unwittingly be spread through contaminated compost. For larger patches, plants can be chipped and spread on-site allowed to decompose.  Alternatively, cut canes can be piled up to dry.  Fresh cuttings need to be kept off of the wet ground to prevent resprouting. Once dried the piles can be brunt, be sure to check with your local Fire District or the Oregon Department of Forestry for suitable burn days.

Follow-Up:

Diligence is the most important aspect of controlling Himalayan blackberry.  Blackberry plants will readily resprout following various treatments methods, so repeated follow-up is required.  The seed may persist in the soil for years following treatment, or arrive on-site from adjacent and nearby infestations.

Best Management Practices:

Small Infestations:

  • Consider the land use practices on site.  Identify, and site-specific considerations that should be taken into account before initiating control.
  • Be sure you can properly identify Himalayan blackberry.  If you are unsure about your weed bring a sample to the Conservation District, and we can help to identify your particular weed.
  • Identify any native or desirable plants nearby, and take precautions to minimize and negative impact on them.
  • Manual removal is very effective at controlling small infestations of Himalayan blackberry.  Plants can be cut with loppers, a saw, or machete at ground level.
  • Use a long board or plywood to mash plants and increase allow access.
  • Dig or pry out the root ball using a Pulaski, shovel, or Shrub Buster.  Remove of as much of the root mass as possible to prevent resprouting.
  • Monitor the site for regrowth, and remove new sprouts as soon as they appear.
  • Small infestations can also be treated using a selective herbicide.  Spot spray techniques work well for small infestations.

Large Infestations:

  • Consider the land use practices on site.  Identify, and site-specific considerations that should be taken into account before initiating control.
  • Be sure you can properly identify Himalayan blackberry.  If you are unsure about your weed bring a sample to the Conservation District, and we can help to identify your particular weed.
  • Identify any native or desirable plants nearby, and take precautions to minimize and negative impact on them.
  • Mow down the blackberry using chainsaws, weed eaters, or a brush mower.
  • Allow blackberry plants to regrow and treat with an approved herbicide.
  • Replant large areas to help stabilize soils.  Start with grasses and allow for treatment using a selective herbicide, then slowing incorporate forbs, shrubs, and trees as blackberry populations are brought under control.
  • Continue to monitor the site for regrowth and treat any new infestations.

Fun Facts:

  • The fruits of Himalayan blackberry are edible and makes great pies and jams.
  • September 29th is Poisoned Blackberry Day!  It is the day of the year that people believed blackberries turned bad for the year and were inedible.
  • "Batology" is the botanical study of blackberry brambles.

Gallery:

Himalayan Blackberry
Himalayan Blackberry
Recursive Blackberry thorns
blackberry leaves
Blackberry thorns on underside of leaf
White Blackberry flower
Unripe Blackberry fruits
Fruiting blackberry
Blackberry bramble

Additional Information:

References:

  1. Bossard, C. C., J. M. Randall, & M.C. Hoshovsky.  2000.  Invasive Plants of California's Wildlands.  Berkeley, CA: University of California Press.  pp 277-281.
  2. Christy, J. A., A. Kimpo, V. Marttala, P. K. Gaddis, & N. L. Christy.  2009.  Urbanizing Flora of Portland Oregon 1806-2008.  Native Plant Society of Oregon Occasional Paper 3 pg. 218.
  3. DiTomaso, J.M. & E.A. Healy.  2007.  Weeds of California and Other Western State vol 2.  University of California ANR.  pp 1426-1434.
  4. DiTomaso, J.M., G.B. Kyser, S.R. Oneto, R. G. Wilson, S. B. Orloff, L. W. Anderson, S. D. Wright, J.A. Roncoroni, T.L. Miller, T.S. Prather.  2013.  Weed Control in Natural Areas in the Western United States.  Davis, CA: UC Weed Research and Information Center.  pp 341-343.
  5. Holloran, P., A. Mackenzie, S Farrell, D. Johnson.  2004.  The Weed Workers Handbook: A Guide to Techniques for Removing Bay Area Invasive Plants.  Berkeley, CA: California Invasive Plant Council.  pp 60-61
  6. Kaufman, S. R. & W. Kaufman.  2007.  Invasive Plants: Guide to identification and the Impacts and Control of Common North American Species.  Mechanicsburg, PA: Stackpole Books. pp 145-151
  7. King County Noxious Weed Control Program.  2011.  King County Best Management Practices for Controlling Himalayan and Evergreen Blackberry (Rubus aremeniacus and Rubus laciniatus).  https://your.kingcounty.gov/dnrp/library/water-and-land/weeds/BMPs/blackberry-control.pdf  (Retrieved May 23, 2013).
  8. Oregon Flora Project. 2013.  Oregon Plant Atlas: Rubus bifrons.  https://www.oregonflora.org/atlas.php.  (Retrieved May 22, 2013)
  9. Peachy, E., D. Ball, A. Hulting, T. Miller, D. Morishita, P. Hutchinson. eds.  2013.  Pacific Northwest Weed Management Handbook: Control of Problem Weeds.  (Retrieved May 24, 2013).
  10. Soll, J. 2004.  Controlling Himalayan blackberry (Rubus armeniacus, [Rubus discolor, Rubus procerus]) in the Pacific Northwest. The Nature Conservancy.  https://www.invasive.org/gist/moredocs/rubarm01.pdf   (Retrieved May 23, 2013)
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