Himalayan Blackberry is one of those invasive weeds whose removal is important, but not urgent. It can be put off for a while, but not forever. September, the end of the dry season, is not my ideal time to work on it, but lacking any urgent tasks in the forest, I was able to get to a patch that was starting to get out of hand.
The weather was too warm to wear a jacket for protection, so I had to slow down and work more methodically. Instead of going in like a warrior waging battle, I used my hand clippers to cut back one vine at a time, until all that was left of the Himalayan Blackberries were stumps sticking up a foot or two out of the ground. Then came the grunt work, prying and popping with a shovel, then grabbing the root crowns and vigorously wiggling and pulling.
This wasn’t the first time I had removed Himalayan Blackberry from this area, and the vigor with which it had come back was a good reminder of the ability of the plant to regrow from pieces of root left in the ground. I knew it came back from pieces of taproot, which can go quite deep, but according to one excellent source, even pieces of major side roots can regenerate new plants. This report, based on a workshop of Pacific Northwest experts, offers six long-term control options and states that “with proper management, infested areas can be restored to desirable vegetation.” (Hope springs eternal?)
One reputable source says, “removal of top growth by mowing, cutting, or grazing with goats will eventually kill blackberry if done regularly and over several years.” In my opinion, I think this only works if it is kept mowed close to the ground through numerous growing seasons.
Biocontrols? In parts of Australia, New Zealand, and Chile, a defoliating fungus, Phragmidium violaceum, has been used to control blackberry. I haven’t found any reports of its use in this country, though in 2005 observers reported that the rust was killing Himalayn Blackberry in Oregon. Personally, I wouldn’t try to introduce it deliberately, for fear that it would also infect our native blackberries.
Other possibilities for controlling Himalayan Blackberry include the Bradley Method to simply contain its spread, cut-stump treatments (on private land), and planting to create dense shade. In reality, there may be no single best practice other than persistence.
I guess we should try to forgive Luther Burbank. After all, if he hadn’t introduced it, someone else in the Pacific Northwest surely would have. It just grows so well here, and the berries are so tasty.