What is the black tar type stuff I see some growers put over wounds after a tree has been pruned or grafted? Do people here use it? Can you recommend a brand and some uses?

Hi!

I believe it is called a pruning sealant. I am not quite sure whether its use is beneficial though as Millet points out:

link

scroll to the very last post.

I've seen it used on Four Winds trees where the rootstock was cut. I still have some on my Kumquat.

I have seen that sealant in two forms: as a thick paint and as a spray. In my experience, the spray is great if you need to fill cracks in the bark of a large tree. For small jobs, spray may be too messy. Anyway, it seems as a petroleum-based product... I do not think that a brand would make any difference.

I buy mine from Ace hardware. It comes in a spray can. Used it today pruning apple and peach trees. I use it on large cuts but not on small cuts.