My 2 yr old blackberry bush is producing nicely this year. There are now, however, 4 suspicious stems that have grown very long and quickly over the past few weeks. They originate from the root area and are single stems. Are they suckers to be cut down or new stems that will produce next year?
This is called a witch's broom and should be removed as it will not produce fruit. In blackberries, it is caused by a fungus. Here is more information: