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Developmental Pruning of Young Trees

By Mark Foster, City of Asheville

 

Hi Again.  Remember back in March when I started my last article with, “You’re the city arborist?  Oh it must be wonderful to work with the trees all day.”  I don’t recall which citizen first said that to me or what year it was, but I have heard it a lot in the 15 years I have been in this role.  I usually just smile.  What I want to say is, “I wouldn’t know, I spend all my time talking with people.”  It’s ok if you don’t remember, but there it is in case you forgot.  The reason I bring it back up is not just to sneak in a free paragraph on this month’s writing assignment. 

No, I actually bring it up because a recent change in my staffing has allowed me to spend large blocks of my day working in actual trees.  I know, it’s really cool and I’m very stoked about it.  The staffing change was that I got a small roadside mowing program and two tractor operators this past July.  Now that the grass is sleeping, the operators are my tree pruning assistants until spring.  I call them my “Green Henchmen.”  “Minions” is more catchy and contemporary, but not very tough sounding so I’m sticking with Henchmen.   Two extra staff, by any name, in an urban forestry program is a very good thing.

What’s most good about it is that it meets a forest management need that had been getting short changed here in Asheville for a while – developmental pruning of young trees.    By “young” I mean planted in the last 15 years.  I usually get in some brand new tree pruning when we plant.  But there hasn’t been the time or staffing to go back a few years later and see how things are going.  Well that’s not quite right.  I have been driving by these trees and noticing their canopies develop wonky structure and often thinking about how great it would be to be able to work on them before they are lost causes. Unfortunately, risk management pruning and removals of the old trees has so dominated my staff’s and my time that being able to spend significant time working with young trees has always eluded me.  Not this year though.  We started with the oldest replantings and are working our way forward.  Many of these trees are large enough for me to climb and that has been the really fun part.  Sure it feels a lot more like work than pecking this keyboard and I’m middle aged and slow in a tree, but so what.  The work is happening and I’m getting out of the office so I can, “work with trees all day.”  I’m also using every trick and technique I can remember from Dr. Ed Gilman’s great outdoor training sessions at the 2015 NCUFC Annual Conference. (Read Dr. Gilman's publication here...)

There are tree species out there that can go several years without much or any pruning and generally don’t develop a bunch of twin tops, poor branch attachment angles, huge lower limbs and other sundry structural defects.  Those tree species weren’t that popular up here in Asheville 15 years ago.  In that age group we mostly have maples and as you may know, they love to develop all those quirks – often in the same tree.  But that’s ok, because my Henchmen and I are on the case.  I’ve also put a lot of effort into species diversification, but that’s a whole other article.

Maybe your community has young trees in a similar condition.  I encourage you to take a look around and see if they are developing bad habits.  Problems are best addressed when they are small.   Intervening before trees get too set in their ways is the key to avoiding structural failures of larger parts that are more damaging to the tree, more costly to clean up and more dangerous to the public.

 Help for a thin-stretched urban forestry program can come