jmcscrap
Participating member
- Location
- Woodbury, MN
I know it is not a good idea to prune trees during leaf drop, but my question is WHY?
Fall Pruning?
- Thread starter jmcscrap
- Start date
- Location
- Midland,Ontario,Canada
The trees will not have the canopy for energy reserves from photosynthesis to properly heal pruning cuts.The trees are preparing for the dormancy stage and therefore storing foods and water for that purpose.(semi educated guess at best)
- Location
- Thunder Bay, Ontario
Am I an idiot here? I've never heard that it's a bad idea to prune during leaf drop.
The only reason that i can think of is that you'd have more leaves to rake up after pruning.
Arborcut: you said the H word....
Vince
The only reason that i can think of is that you'd have more leaves to rake up after pruning.
Arborcut: you said the H word....
Vince
- Location
- Midland,Ontario,Canada
I could feel the daggers comin as soon as i typed it,my bad.
- Location
- central texas
Shigo often recommended abstaining from pruning in the fall when he gave lectures. In his "New Tree Biology" he states "be very careful when pruning during leaf shedding... if possible avoid pruning at [this] time" Unfortunately, nowhere in this book does he say why. I seem to recall it having something to do with callus formation being slower then, probably related to what ArborCut suggested.
However, my personal experience over 30 years is that time of year is not nearly as critical as how conservative you are, that is how many live branches you are removing. There are of course regional exceptions for particular species and insect/ disease problems, but in general, I do not believe there is any reduction in CODIT from conservative fall pruning.
Shigo also recommended avoiding pruning during bud break and leaf expansion. Again, no explanation in NTB, but obviously, trees are very busy doing something very important during that time, and I personally try to avoid any live branch removal then.
Aggressive pruning will almost always have a host of ills associated with it, perhaps especially problematic in spring/ fall. Although at times necessary, certainly best to avoid it.
For years our industry considered aggressive pruning as removing more than about 33% of the canopy. Now the rule of thumb is 25%. I NEVER exceed 10% unless I am doing weight reduction for some kind of defective tree or branch. I wish ISA/ TCIA would support a more conservative recommendation. Overpruning is the biggest health care threat to trees in my part of the country.
However, my personal experience over 30 years is that time of year is not nearly as critical as how conservative you are, that is how many live branches you are removing. There are of course regional exceptions for particular species and insect/ disease problems, but in general, I do not believe there is any reduction in CODIT from conservative fall pruning.
Shigo also recommended avoiding pruning during bud break and leaf expansion. Again, no explanation in NTB, but obviously, trees are very busy doing something very important during that time, and I personally try to avoid any live branch removal then.
Aggressive pruning will almost always have a host of ills associated with it, perhaps especially problematic in spring/ fall. Although at times necessary, certainly best to avoid it.
For years our industry considered aggressive pruning as removing more than about 33% of the canopy. Now the rule of thumb is 25%. I NEVER exceed 10% unless I am doing weight reduction for some kind of defective tree or branch. I wish ISA/ TCIA would support a more conservative recommendation. Overpruning is the biggest health care threat to trees in my part of the country.
- Location
- Penticton, British Columbia
At budbreak, and leaf senescence, the tree is expending a great deal of energy in order to:
In the former case, the tree is establishing the logistics for the 'food factories' for the growing season. It is moving a great deal of water, reserved carbohydrates and starches from the trunk and root system to the stems and twigs which will support the aforementioned food factories. The reserves will be there in the event the tree needs to establish neoformed leaf buds or take advantage of favorable growing conditions.
In the latter, the tree is actually withdrawing as much energy that it can from the spent leaves, and pulling whatever carbohydrate or starch reserve that it can from the twigs and stems, and downloading these excess reserves into the trunk and root system. Preformed buds are established and made ready for the following growing season.
So, if we prune, even a conservative amount, during these sensitive times (which generally only last 1-2 weeks per individual tree and vary by species), the tree may be robbed of the ability to transport and utilise excess reserves of starch, carbohydrates and water. Obviously, trees will be better able to handle the stress of a conservative pruning vs. a heavy prune. Proper abscission is necessary for the tree in order for it to remove what little energy it can from each leaf.
Am I wrong, or can someone explain it better?
In the former case, the tree is establishing the logistics for the 'food factories' for the growing season. It is moving a great deal of water, reserved carbohydrates and starches from the trunk and root system to the stems and twigs which will support the aforementioned food factories. The reserves will be there in the event the tree needs to establish neoformed leaf buds or take advantage of favorable growing conditions.
In the latter, the tree is actually withdrawing as much energy that it can from the spent leaves, and pulling whatever carbohydrate or starch reserve that it can from the twigs and stems, and downloading these excess reserves into the trunk and root system. Preformed buds are established and made ready for the following growing season.
So, if we prune, even a conservative amount, during these sensitive times (which generally only last 1-2 weeks per individual tree and vary by species), the tree may be robbed of the ability to transport and utilise excess reserves of starch, carbohydrates and water. Obviously, trees will be better able to handle the stress of a conservative pruning vs. a heavy prune. Proper abscission is necessary for the tree in order for it to remove what little energy it can from each leaf.
Am I wrong, or can someone explain it better?
Outstanding explaination Dylan! Exactly as Dr. Shigo would have explained it. There is also the added threat of high spore populations that occur in the fall of the year increasing the opportunity for fungal infection of the fresh cuts. In Shigo's Modern Arboriculture there is a graph of the energy consumption during the course of a year. I will post the page reference tomorrow when I can check my copy at my office.
Reference Shigo: Modern Arboriculture P. 271, Askenasy Potential Energy Curve Graph along with some insight although inconclusive, from the Master. When he spoke about this at the Penn-Del ISA symposium sometime in the '90s, it was an AAAHH moment for me. Of course for anyone who has had the good fortune to attend a presentation by Dr. Shigo, there were many AAAHH moments during his presentations. I miss the Gentleman. I don't rightly know if I could call him a friend, but he knew me by name.
