How do I get rid of blackberry plants?
Many people in the Northwest have conflicting attitudes about wild blackberries. A handful of ripe berries or a piece of fresh blackberry pie is a scrumptious treat. On the other hand, it’s easy to hate the brambles that take over a back fence or a creek bed. If you decide to get rid of unwanted blackberries, you’ll be faced with a resilient and thorny plant. It’s not true that removal of these plants “must rely on foliage-applied herbicide treatments.” With a little persistence you can remove unwanted blackberries without using chemical poisons. (see Blackberry Plant Biology page)
Don’t Forget Disposal
All blackberry removal techniques (except grazing) will leave you with dead or dying plant material, most of it thorny. Before you start, figure out how you will cope with this material. In an urban setting, your own compost pile is a good solution. Alternatively, find out if your community offers a composting program, or if a local business accepts yard waste for composting. Then decide how to bundle and transport your material. In natural areas, the waste material can be piled and left to decompose. Sprouting from these piles is rare, and the piles will disappear relatively quickly. Smaller amounts of blackberry stems and crowns can be piled on logs, or hung from trees to dry out.
Dress for Success
Whatever removal technique you choose, protect yourself from thorns.
Leather gloves, sturdy boots, a long sleeved shirt, and jeans or other tough
pants are all essential.
Mowing and cutting: One technique for removing unwanted berries is mowing or cutting. “Cut back the vines to ground level,” recommends Oregon State University extension weed scientist Jed Colquhoun, “especially in the spring when the plant is most actively growing. Cutting vines continually back will eventually kill the plant, although it may take some time.” If you’re trying to turn a blackberry patch into lawn this is an ideal technique. The repeated mowing that your lawn requires, along with the competition from grasses, will kill the blackberry plants. You’ll probably want to cut and remove the stems and leaves of good-sized plants before you mow for the first time. In a small area, loppers or weed whackers can substitute for a mower.
Covering the soil after cutting or mowing can be an appropriate way to kill roots and crowns. A thick dark material will keep light from reaching new sprouts from roots or crowns so they can’t grow. Use this technique to transform, for example, a blackberry patch into next year’s garden.
Digging: Digging out blackberry crowns is another effective removal technique. The Nature Conservancy calls digging blackberries “a slow but sure way of destroying” this plant. This technique, which specifically targets blackberries, is useful in areas where preserving the neighboring vegetation is important.
In Oregon’s Tryon Creek Natural Area, enthusiastic teams of volunteers led by two dedicated coordinators are successfully removing blackberries from large areas using this method. Volunteers (nearby residents, employee teams from a local utility, and county community service crews) provide the labor. According to coordinator Dave Kruse, effective digging doesn’t take special techniques. He tells the volunteers to dig out the crown and tells them they don’t need to worry about all the little roots. Generally, they have found that persistence determines success. They don’t clear areas that they don’t have time to maintain. They go back about a year after the original dig and remove any new plants. Typically the number of blackberries at that point is about 1/4 of the original amount, but they are easier to dig because they don’t have large crowns. After that work is done, they find they only have to check on an area about once every three years. They also plant native conifers in newly-cleared areas, since blackberries don’t thrive in shady areas. In four years, the volunteers have taken care of most of the blackberries in half of the 645 acre park. Digging blackberries doesn’t require any tools other than an ordinary shovel or spade. However. some diggers have found a claw mattock useful. The “claw” pulls out plants like a claw on a hammer pulls out nails.
Goats have a long history of use for blackberry control, particularly in Australia and New Zealand where they have been used since the 1920s. Goats eat blackberries readily, and seem to prefer them over other plants. In economic analysis in Australia showed that running goats on a blackberry-infested pasture was cheaper than using herbicides to manage the berries. Clearly, goats are not suitable in all locations, but in pastures they may be an excellent option. Use of goats could also be considered in firebreaks, utility rights of way, and other similar sites.
Many people in the Pacific Northwest sympathize with the Oregon resident who reputedly said, “If we all left the valley, in three years Himalayan Blackberry would prevent us from getting back in!” However, with an understanding of the biology of this weed and a little persistence, it is not difficult to manage blackberries without pesticides.
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