Heya, I have row of blackberry plants that I planted last year. Everything grew fine and started blooming well this year. However the canes are very long and very skinny. I think the amount of fruit on each cane is is to much for it to support. I am thinking of just cutting all of the cains back to the ground so that I will have thinker healther cains next year. Is it ok to prune all off the cains off at this time of year?