You tip root (also called tip layer) on the primocanes (first year growth). Once the fruiting is done the cane dies and should be removed. If your Ouachita blackberry is growing properly, you should have several new canes popping up to replace the fruiting cane. Sometimes the new growth is hard to see at first because it hides under the second year growth. If you look at the canes under the current leaf cover, the new canes should be lighter green.

I have 5 Ouachita blackberry plants in the ground and they are about 50% complete with blooming (in zone 6B). I have some new canes that are already 4-5ft tall by comparison.