Shoutout to the old timer in Portland who told me to stop using a pruning seal on oak cuts

3 comments

3 Comments

93 year old guy in the parking lot of Home Depot told me the same thing about 10 years ago. He said "that goop just traps moisture under there and rots the tree from the inside out." I felt like an idiot for buying three cans of the stuff. Haven't touched it since.

henryp401mo ago

Gotta disagree a little bit on the exact science there. The old goop isn't really about sealing moisture in, it's more that trees actually do a fine job of sealing their own wounds if you just leave them alone. Pruning paint was invented for people who couldn't stand looking at a fresh cut and felt like they had to do something. I've got a couple of oaks I trimmed three years ago and never touched with anything. They healed up clean and tight. The real issue with that stuff is it can actually keep the tree from drying out properly after a cut, so yeah, moisture might get trapped under there and cause rot.

milam481mo ago

My neighbor's oak took a bad limb split about 8 years ago, and I painted the wound with pruning sealer. That branch never closed up properly and I ended up having to take the whole thing down last spring. @charles_mitchell your Home Depot guy was right from what I've seen. I dug into it a bit and the arborist at our local extension office told me the same thing - trees have their own built-in chemistry for compartmentalizing damage, and that goop basically short-circuits the process. I've left all my cuts bare since then and they heal way faster. The only exception I'd make is if you're pruning during an active oak wilt season in your area, otherwise let the tree do its thing.