Last year I posted some obscure thoughts on pruning to point out why animals nibbling the food forest citizens, although harsh at first look, can not only heal but have a beneficial effect on the trees ability to fruit.
This year I’ve witnessed a new form of pruning, one that doesn’t happen in winter, but during the growing season. What’s most bizarre about it is it’s plants pruning themselves.
The first was one of my two snow peach trees that were weeds out of a friend’s flowerbeds. Winter before last it was nipped on the top branches during the era of goats and so decided to stop growing, sending up a new shoot from the roots. These two shoots side by side worried me, because I knew if the tree was allowed to grow this way the two sides would crack apart, or rub on each other, and cause a whole host of problems for the tree.
Despite the risk, I decided to withhold the nippers and watch. About midsummer the leaves of one sprout dropped, but started growing vigorously in the other, by its own choice.
I have read about this phenomena as explained by scientists who study plant hormones. Certain chemicals in the plant prefer to have one leader, but usually do this by stimulating new buds further down the stem if the leading tip is harmed. I guess because the tree was so young (only about two feet tall) it decided to send the new growth from where the hormone that mostly dictates this process comes from, the roots.
What really surprised me was the timing. It wasn’t until well after the two branches had leafed out and seemed perfectly healthy that suddenly the one started losing its leaves. I wonder if it just took that long to go through the process of stimulating the hormone that cuts off sap flow to damaged branches.
Another plant-self -pruning was by my apricots. Both are on their own roots, but one came with a very nice, uncut structure, the other had its leader shoot nipped off in favor of an unruly side shoot, for which I’d like to examine the genius arborist’s head. But no matter, I left the tree as it came.
After a year of it trying to figure out what to do with such a disproportionate branch on its side, it has decided to pull all its nutrients out of that branch and just start over by sprouting from the main trunk. I don’t mind this in the least because it looks like this will make for a more bushy, shorter habit I can more easily harvest.
The other, better structured apricot is doing the exact opposite. It took one branch out of the several it had and decided to make that the leader in a dramatic kind of way: one branch stood still and the other grew over four feet! Then just the other day I noticed a rabbit had stretched high enough to bite the whole lesser branch off and left the other unharmed. Tell me how that works?
So these were the standouts of my trees’ decisions to moderate their growth for the better, and I fully stand behind their decisions with complete approval.
Of course the trees in all these situations are on their own roots. Grafting a tree onto rootstock far too small for its genetics, also known as dwarfing a tree, does change things up a bit, since many of the said hormones are manufactured in the roots. Such is my opinion anyway. But the fact is the effects of dwarfing aren’t very clearly known accept that it speeds up the aging process of the tree. For instance, see this study.
Whatever the state of your tree, I would recommend to at least not be hasty with your pruning craze, to wait to see how the tree reacts, and to have faith in its ability to manage itself. Because as you can tell, they often make very distinct, beneficial decisions all on their own.