Stupid creatures – trees just stand there and take barrage after barrage of abuse from Mother Nature, other living creatures and people. Winds blow their branches off, rodents snack on their bark for winter munchies, and sap suckers drill holes in their trunks as they forage for insects.
Do you “heart” your tree? Trees deeply wounded have difficulty recovering.
Photo Credit: Bonnie Lee Appleton
Sap suckers drill holes in tree trunks as they forage for insects.
Photo Credit: Bonnie Lee Appleton
This is “woundwood” – callus tissue that forms at the wound site. Its presence means the tree is healing.
Photo Credit: Bonnie Lee Appleton
As is that weren’t bad enough, there are the “tender loving care” things that people do to trees: We drill holes in them to inject micronutrients or pesticides; we hack off dead, broken and diseased branches; we cable large branches together to prevent splitting; and we install lightning protection on them.
More often, people do lame things like whack poor trees with lawn movers, use them as sign posts or lop off their tops if they think they’re too big (or just in the way). We also run into them with cars, dig up their roots and peel their bark off as if it were shedding sunburned skin.
Regardless of who attacks our trees – or how or why – these constant activities all have one thing in common: They create wounds. Whether large or small, round or square, smooth or ragged, wounds cause trees to expend energy in order to help them deal with the damage.
The ability of trees seal their wounds (compartmentalize) varies by species, age, season of injury, vigor, wound location, exposed tissues and other factors. One goal of current tree breeding research is to identify tree species that have superior wound-closure capabilities. But until all of our trees are super closers or learn how to run away or fight back, it’s up to us to give our growing friends the best environment we can.
For the sake and love of trees, the best practice is never to wound them at all. But if they must be wounded for some reason, we should do so responsibly.
If we prune, we should always try to make our cuts just outside the branch bark collar for total branch removal, or just above an outwardly facing bud for partial branch removal. If a tree or its pruning job is too big for you to handle, please hire a certified arborist.
If a tree wound consists of an area with torn bark, don’t pull the detached bark off. Instead, cut torn bark off just beyond its attachment point to the tree. If a jagged wound is left, use a sharp knife and cut a smooth edge around the wound, cutting just barely into the bark and wood around the wound. Follow whatever the shape of the wound is – there’s no need to make things symmetrical. Callus tissue will start to grow along your cleanly cut wound line.
Regardless of what you sometimes hear or see, don’t apply external products to tree wounds. None of the so-called “tree wound products” sold by garden centers or mail-order catalogs aid wound closure, and some have actually been shown to be toxic to tree tissue. There are a few rare exceptions where wound products may be beneficial, of course – when dealing with attacks by certain borers and with oak wilt infections, for example – but that relates to reducing pest problems, not helping the trees seal their wounds.
So please take this hint to heart: Trees aren’t nearly as tough as they appear, so make certain you respect their roots, trunks and branches – love them, don’t wound them!
