You may want to rein in the blackberries. Ours run along a fence line near our front gate-driveway. We cut them back hard every year and every year they grow back and do their best to grab, scrape and poke us when we go in and out. Taking out the older, largest canes helps to encourage new growth. Blackberries fruit on new canes. They will sprout almost anywhere from cuttings left on the ground in fertile soil. Mine also run by roots and have them sprouting up in the potting area. Wild blackberries are both a blessing (baskets full of fruit, leaves for tea) and a curse (scratches, pokes and splinters). Muscadines need support as they are prolific climbers and will bear a heavy load with their fruit. They also fruit on new vines and should be cut back annually. Most folks here (GA) trim their muscadines in Feb. but anytime is fine if they need it. I forgot about pruning one year and they grew into the oak tree and over the fence into our pasture. Our horses like the fruit LOL. Happy growing!