October Weed of the Month: Blackberry

Invasive blackberry photo by Sam Leininger

Invasive blackberry photo by Sam Leininger

You wrangled with the prickly vines in the spring and enjoyed those juicy sweet berries all through the summer, but now it’s fall and it’s time to take control of the October weed of the month: blackberry! So, put on your heavy-duty work gloves and get to work on those vines! That’s right — autumn is the very best time to control this wide-spread and aggressive invasive.

Protect Creatures and People!

One reason to control blackberries in the fall to avoid disturbing nesting birds. In the spring, some birds will use the thorny brush to build nests and hatch their eggs. If you choose to use a chemical control, you will also want to avoid taking action when the plants are in bloom. Many of our important pollinators such as bees and butterflies may be at risk during flowering. When berries are on the canes, it is not only birds, but also people and other animals that are at risk from chemical applications. Fall is the safest time to control chemicals. Remember, ALWAYS FOLLOW THE LABEL and put safety first, for you and any unintended targets.

Pull On Gloves!

For manual control, it is important to arm yourself against the sharp thorns by wearing thick gloves, sturdy long pants, and long-sleeved shirts or jacket. Those who are unprepared will suffer the consequences with nasty scratches. Use board or plywood to mash down blackberry canes, and to access densely infested areas. If your ground is level or has little slope you may also be able to mow down the canes (sometimes a brush cutter is necessary). This will remove the bulk of the plant. If you wish to use the mowing method for permanent control, you will need to continue this process at least 4 times per year, for several years, to exhaust the energy in the root system. Remember to check for any nesting birds in the spring, but if you keep on top of the mowing there will not be a good place for the birds to build a nest. If using goats to remove the blackberries, you may still want to get rid of the old canes first and then let the goats periodically graze the new growth for long-term control.

Can You Dig it?

If you choose to remove the entire plant, including the roots, you will have much easier access with the top growth removed. Digging or tilling can take out the root system, but be sure to remove as much root material as possible. Even small pieces can re-sprout, so try raking up all remaining bits. If you are working on a slope, make sure you have enough time in the fall to reseed any disturbed areas to avoid erosion caused by fall and winter rain. If not, root removal might need to wait until spring.

Weed Alert!

Warning: expect a flush of weeds in the old blackberry patch. A build-up of weed seed may remain dormant under the brambles for years and once exposed to sunlight they will sprout. Weed control is just another step in the process.

Removal of invasive blackberry requires persistence and patience, but success comes to those who persevere! For more detailed information on blackberry control, check out our Best Management Practices on the WeedWise Website.

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Clackamas SWCD