Planted them 2 years ago and we have neglected them. How do we recover them?
Here is a link to help you get the blackberries back in shape.
https://www.gardeningknowhow.com/edible/fruits/blackberries/blackberry-pruning.htm
Last year I planted blackberry canes and harvested a few berries. This year, each cane has a large "sucker" type growth that is quite large in diameter and has no blossoms on it as do the other smaller branches. This is why I think they are suckers. Should I go ahead now and prune those large suckers or might this be next year's "wood" for berries? Thanks for any help.
Here is a link to pruning your Blackberries.
There is both tip pruning and clean up pruning information.
https://www.gardeningknowhow.com/edible/fruits/blackberries/blackberry-pruning.htm
Stems coming up with the blackberries are very similar but the blackberry stems have 3-leaf clusters and the new growth has 5-leaf clusters and, as yet, no evidence of fruit. I do not know if other blackberry varieties have a different leaf arrangement. Do you have a suggestion?
Blackberry leaves can be 3 to 5 leaflets.
Here is a link.
http://www.hort.purdue.edu/ext/senior/fruits/blackberry3.htm
We have blackberries that came with the house along a block wall about 15 feet long. Trellis consists of wires screwed into the wall. The first picking (about 2 weeks ago was a little early). The fruit we are now getting is smaller, some to a point where the fruit is all seeds and very little flesh. What is causing this? We also planted some thornless blackberries 2 years ago at one end. That fruit is longer, more like a mulberry. Fruit on the newer plants also appear smaller than last year. What could be causing this? If I can feed to rectify it now, we have about 1/2 of the fruit that is ripening left on the canes. Otherwise, we will have to try your suggestion for next growing season. Thanks.
Environmental effects, lack of pollination are possible reasons.
Here are some links with more information.
https://www.gardeningknowhow.com/edible/fruits/blackberries/blackberry-pruning.htm
https://www.gardeningknowhow.com/edible/fruits/blackberries/blackberries-not-fruiting.htm
https://www.gardeningknowhow.com/edible/fruits/blackberries/what-are-marionberries.htm
I have a blackberry tree in my yard and last year it produced a lot of fruit. In past years, it did not bear any fruit. This year it is producing fruit again. The tree has been in my yard for over 30 years.
I believe you may be referring to a Mulberry Tree.
The environment and it's changing weather can effect how much or even if the tree bears fruit.
Many gardeners dislike the mess from Mulberry fruit.
Here are a couple of links.
http://www.fruit.cornell.edu/mfruit/mulberries.html
https://www.gardeningknowhow.com/ornamental/trees/fruitless-mulberry/mulberry-fruit-sterilization.htm
I planted 3 Prime-jan blackberry plants this spring. Can you give me any information on their care?
This article will help you: https://www.gardeningknowhow.com/edible/fruits/blackberries/growing-blackberry-bushes.htm
We are growing blackberry plants and actually have blackberries growing this year. We planted them last year. There are a few "super" branches, that is, thicker, woody, branches that don't have fruit on them. Are these some kind of dormant or sucker branches and should they be trimmed or should we leave them? Can you explain to me what they are?
Yes, they should be trimmed. It sounds like you have witches' broom on the plant. In blackberries, it is normally a nuisance more than harmful to the plant, but they sap energy away from fruit production and will not produce themselves so it is best to remove them. This article will explain more about the condition:
https://www.gardeningknowhow.com/ornamental/trees/tgen/witches-broom-disease.htm