I originally posted this over on the fruit and orchard forum, but I think it would be better here. I hope no one minds the cross post.

We have several acres of woodlands and a large (1/4 acre or so) wild blackberry patch. Last year we had some Japanese Beetle issues, but for the most part the canes were healthy, though the berries were small due to the weather. This year however, the fuiting canes look terrible. They're covered with small berries (dry weather again) but the leaves are brown and spotty and sparse. Oddly enough, the new canes that will bear next year look very healthy - not a hint of the discoloration and browning of the fruiting canes. I've attached photos from about 2 weeks ago - they look worse now.

Do we have a disease? Could this just be because we've had odd, hot, humid weather, but little rain? Could they just be choking themselves out? It's quite overgrown and really, just a big tangle of canes. Can I do anything to rejuvenate this patch? We're considering just mowing down the whole field and trying to get the healthiest canes to grow in some order. I know they'll come back, as we cut some down this spring in anticipation of a cabin being built and they're coming back in those places. I LOVE wild blackberries and this is not a place we live, just visit occasionally, one or two times a month at most, so I can't actually cultivate anything that requires much work, but I don't actually know much about taking care of them at all. We need to do something, if for no other reason than it's so hard to get in among them to pick.

If you have any ideas of what we can do to rejuvenate these plants and get them producing better berries, I'd really appreciate a response. Thanks!

1st pic - Healthy Primacanes

2nd and 3rd pics - browning leaves and stunted fruit