Jim Fruth asked whether Doyle blackberry would produce after a normal
winter.
If you read the fine print about Doyle, you'll find they are claimed to be
hardy in zone 5 and below only if vines are covered for the winter. To me,
that's not hardy, just excessive work. I never got a crop without covering.
(Maybe one could get away with it if there is sufficient snow cover all
winter.) And yes, they do sucker for me. I'm not quite rid of all of the
plants and their suckers, but I'm still working on it. On the good side,
they are, indeed, thornless.