This is the time of year I go after the invasive plants that live among the big trees on our lot. The worst offenders I have to deal with are English ivy, Himalayan blackberries, and English holly. None is fun, but the blackberries put up the best defense, and despite wearing gloves, by the end of the day I have plenty of thorns in my fingers and more than a few scratches.
Really getting rid of blackberries requires a bit of understanding about the plant. The canes grow from a crown and root clump. Canes are viable for two to three years before they die, producing fruit on the side shoots of second year canes, much like raspberries. The canes grow vigorously, and reach lengths up to forty feet, winding through tree branches, often looping over and finding the ground again. When the bramble comes in contact with the ground it can develop another root ball that will become another crown the following year. In this way, the brambles can leapfrog along, quickly spreading and colonizing the surrounding area. Just cutting the plants back year after year only seems to make them healthier, though it does reduce the spread from the ends of the canes.
I think the best control technique is to pull the plants up at the crowns. This time of year, the undergrowth has died back enough that you can find the offending plants easily, and the ground is moist enough that you have hope of getting the roots out. I loosen the clump with my garden fork, and then PULL with well gloved hands. Good leather gloves are a must! You will get the main clump, and the brambles will follow, but then you will notice that the ends of the canes are tied to the earth.
Each end that has started its new root ball must be pulled by the roots as well, or you will be doing this job again too soon. After pulling all the brambles that you can find, you will still miss a few roots. In a couple of months new shoots will lead you to the ones you missed so you can go back and finish the job.
By June I’m always looking forward to the first blackberry blossoms. There is an uneasy existence between the beekeeper and the ecologist when it comes to invasive species. As a beekeeper, I like all the blackberries around here, just NIMBY! In many places non-native species become dominate honey crops. Locally we have invasive star thistle (knapweed) and purple loosestrife in addition to the Himalayan blackberry that can produce major honey flows. In the fall, the English ivy that grows up into the trees will flower and be abuzz with bees, as will the English holly trees. But despite the nectar potential, I try to keep the invaders under control. My reward is a carpet of wild violets in the spring.