Pruning during leaf formation

[dspacio]

I know I read that it's best to avoid pruning during a ~2 week period when the tree is real actively forming and growing it's leaves.
Being in the work world we live in, with many factors, where we may be pruning in this window..
are there any precautions or approaches to limit the effect?

My memory may have been Gilman's Pruning book, I will look for info to add, why they mentioned this.
I notice extra tendency to tear, even on a clean careful finish cut, bark is ready to peel away. (I was in Maple) And of course the tree Just used all that energy to make the leaves and totally loses out on any return.

Been on my mind that past few weeks as things are greening up,

 

[oldoakman]

Shigo preached refrain from pruning in the spring while leaves are forming from bud swell to full extension and in the fall from color up to abscission. In spring as you said from the reallocation of energy reserves from leaf formation and growth to wound response and in the fall from fungal spore activity. Good question.

 

[Serf Life]

Peaches can be pruned while flowering, there’s probably a few other exceptions. Apples are a definite no go and are prone to sooty mold then black rot. Haven’t seen a huge difference with oaks but would try to schedule removals preferably.

 

[Tom Dunlap]

In a Shigo Session I learned about the spring/fall pruning issues. I wish I knew the books better so that I could provide chapter and verse explanations.

The tree needs energy to grow and shed leaves. If the tree is wounded it will shunt energy to isolate decay rather than what it really needs to do which is grow/shed.

My policy was to not do any pruning of large limbs during those times. Stick with other work or make sure the work requires only very small cuts.

The whole issue of diseases is separate to energy allocation.

 

[Phil]

And of course the tree Just used all that energy to make the leaves and totally loses out on any return.

This is kind of a misnomer. Inside the dormant bud, the leaves are already there, just really tiny and essentially dehydrated. They were formed with energy from the previous years growth cycle. When spring time comes and the tree is triggered to start growing again, all it has to do is move water with nutrients into the bud to expand the leaf cells that were formed the year prior. Think of it like inflating an air mattress, just with water instead of air. A tree needs leaves to produce carbohydrates for fuel. In the spring it has no leaves so can produce no fuel. This also means that pruning off a live, dormant branch in the winter removes exactly as much energy as removing the same branch in the spring as it just starts to leaf out.

Pruning in the spring has proven to be ideal for maximum pruning wound closure because the tree is actively growing and can immediately start its defense mechanisms. But on the other hand, spring time is also when some pathogens and insect vectors might start moving....and looking for new fresh exposed wood to munch/propagate on.

 

[DSMc]

From my experience, the cautions about early pruning have not panned out to be true. Aside from the aforementioned need to be aware of pathogens or pests, most trees respond favorably to early pruning, when they are most capable of producing new tissue.

The concerns of weakening health through resource removal has far more to do with dose than timing.

 

[Tom Dunlap]

The concerns of weakening health through resource removal has far more to do with dose than timing.

That's the essence of the issue

 

[Lupin_IV]

I watched a Gilman lecture recently where he mentioned this and I believe also confirmed in A New Tree Biology. not detrimental alone but may tip the scales if something goes wrong. Something along those lines. I will try to find the book passage if I remember next time I pull it out.

 

[KTSmith]

Yes, the recommendation was from Shigo. It is a belief based on .... a logical extension of the reasonable expectation that when the tree has a lot going on, it's best avoid treatments that require resources from the tree.
But yes, DSMc is ahead of me here. Keep in mind that when Shigo was most deeply into traditional research (1950s-1970s), he was just trying to keep folks from flushcuts, topping, and tarry wound dressings. And Phil is quite right, wound closure, at least for the first year, does close faster with early spring injury. Shigo argued with Dan Neely and Curt Leben from dissection that internal compartmentalization was independent of closure rate.
By the 1980s, he was moving faster and further than his actual field and lab experiments. In lectures at that time, Shigo often began statements with "I believe that....". Practitioners had no problem with that, you guys cheered. Some of those beliefs became enshrined and institutionalized by practitioners. The research forest pathology and mycology communities could not accept that, so Shigo threw his fortune into practical arboriculture as he found it.
For arboriculture and Shigo personally, I think it was a good series of events, but as an active (?) forest pathologist myself I recommend (1) Avoid pruning oak in oak-wilt-land when the vectors are flying around. Your local extension folks should have dates for that; (2) Use sharp tools appropriately; (3) Position cuts to promote compartmentalization; (4) Get paid for honest work.
For the very limited research on seasonality, the time to avoid would be late fall / early winter due to the lag time of the tree's metabolism to full respond to the injury. Timing is less important than 1-4, above.
But yes, I also believe that it's best not to ask the tree to do a lot when they have a lot on their mind.

 

[Tom Dunlap]

Thanks for the insights Kevin.

I remember the days of flush/collar cut issues.

At one presentation Dr. Shigo suggested that we do vertical dissections of removals like he had done out in the woods. Over time I found shrubs with multiple cuts, some flush some collar, which allowed me to dissect with my Felcos or bandsaw back in my woodshop. No need to wait for years to see how decay was isolated.

 

[dspacio]

Wow, I never thought of it that way @Phil . I do remember reading the benefit of pruning in the Spring too, where the tree is so active it is able to heal wounds readily.
Another instance of multiple pieces of information, seemingly (directly?) contradicting, to make sense of.

thanks for the input everyone.
I am still noticing the tendency for bark to tear more with so much flowing underneath that layer. So I am being a bit extra careful on that final slice of the pruning cut.

I am staggered at how much information in tree work are just things that have been repeated; maybe a step above superstition.. but enough people say it so it goes as true.

The latest one I keep running against is "Raising the canopy" but that's a whole other can.

 

[ATH]

....
I am still noticing the tendency for bark to tear more with so much flowing underneath that layer. So I am being a bit extra careful on that final slice of the pruning cut.

I am staggered at how much information in tree work are just things that have been repeated; maybe a step above superstition.. but enough people say it so it goes as true.

The latest one I keep running against is "Raising the canopy" but that's a whole other can.

1) No question more bark tearing in the spring. Tulip-poplar logs have been known to slide off of log trucks "naked" leaving their bark behind in the spring. Thinner bark maple trees are a challenge to climb this time of year because the bark will rub right off. etc...

2) A lot of those mis-information things related to trees seem intuitive at first glance. "The tree is hollow, that means it is weak. We should fill it with something strong - like concrete." "The tree is too tall...logically, we should top it. They sprout back (most of the time), so why not?" "Don't like topping? - well, lets take all of the branches except those at the end." "Surely thinning out the tree will cut down on the wind load the trunk has to bear." etc...

3) Raising the canopy... Sometimes that is just necessary to allow for traffic clearance/public safety. When somebody wants it for purely aesthetic reasons and it is going to be taking too much, I'll point out the need for patience. "We'll get there - just need to give the tree time to be tall enough before we clean up the lower branches. I know you want it to look nice...but I think alive always looks better than dead." I went to school for traditional forestry, so I think every tree should look like it grew up in the woods

 

[dspacio]

@ATH : I went to school for traditional forestry, so I think every tree should look like it grew up in the woods

Absolutely! The forest remains the template, with a seasoning sprinkle of the Garden.

One crew I climb for, every time the day is just "cut this one, cut that one," as if each visit, removing the lowest layer is going to reduce risk or allow more light in. It only takes one leaf to cast a shadow, and the tree has leaves going up forty more feet...

Makes me really appreciate the relationships I have where my job is "prune the tree, remove deadwood, wounds or disease. maybe one decent structural change".

Has me thinking about the existential crisis of certain days/tasks in the trees, but maybe that belongs in the "Dead wood" thread