New Shoots on Blackberries

Question

I have inherited some blackberry bushes on my allotment. Both varieties are thornless and I pruned according to instructions. However, I now have some very vagrant new shoots coming up, which have thorns. These shoots are very strong. Why is this, and do I need to cut them back to ground level?

Answer 1

Some varieties of blackberries are blended with others to create a blackberry that is thornless as the plant bought, but that will revert to a thorny blackberry if propagated. These sucker are a form of propagation (though not intentional), so they grow with thorns. It would be best to cut out the shoots that have the thorns.