May 2015

Invasive Watch: Blackberry (RUBUS SPP.)

There are several varieties of wild blackberries, including Himalaya, cutleaf and California, common in North America. Most are similar in that they produce vines that rise from a central crown or from buds that form along rhizomes. Plants are covered with sharp thorns and typically have between three and five leaflets with roselike flowers at the end of the shoots. It also produces tasty black fruit when ripe.

Blackberry is found throughout North America. It routinely inhabits roadsides, pastures, field edges or natural areas, and it thrives in soil around rivers and wetlands. Its spread is facilitated by the many animals that eat its fruit and spread the seeds in their droppings. These seeds have a hard coat and may remain dormant for a long period. A single plant, left untreated, is capable of covering a large area over time. Wild blackberry plants have been known to live for more than 25 years.

How to Treat It
Apply either Opensight® specialty herbicide at 3.3 ounces per acre or Milestone® specialty herbicide at 5 fluid ounces per acre plus Garlon® 4 Ultra specialty herbicide at 2 pints per acre. Treat when leaves are fully expanded and the plant has stopped rapid spring and early summer growth. The optimum application window is after bloom and before frost. Additional follow-up treatments in a multiyear treatment program may be required for effective control.