North American Fruit Explorers mailing list at ibiblio

[Alan Haigh <alandhaigh@gmail.com>]

My take on whether or not summer pruning will be dwarfing is that if you actually substantially reduce the amount of light harvested you will reduce growth.  If on the other hand you simply remove surplus harvesting capability, essentially reducing shading and enhancing efficiency, no dwarfing will occur.

 

I would like to see this theory actually put to test- it would be very simple.  Reduce the shadow of trees by say 30%, such as by by cutting out entire scaffold branches, leaving large holes in the canopy.  I believe that winter pruned trees would do a better job of recovering that lost light and would ultimately loose less vigor by the treatment.  Anyone seen any experiments similar to this? 

 

This is certainly more like the kind of pruning I do when I do structural pruning of big old apple trees then the "moderate" shoot pruning described by Ferree in research noted by Reich.  I often eventually steer the trees to a structure that will harvest that lost light but  that can take several years.  Sometimes I bring trees in and shrink their range but I would assume that this would be about equally dwarfing whether done winter of summer- at least in the long run.  That's because the ability to harvest that light is not recovered whether branches are pruned winter or summer.

 

One interesting question to me is where harvested energy goes, based on whether the wood is fruiting or vegetative.  Obviously spur leaves are going to send much more energy to fruit production then to new wood (the basis of vigor).  Trees start to slow down once they start bearing fruit but I used to think that annual wood (their leaves, actually) sent more energy to the roots (as well as to new wood) then spur-wood.  Ferree's research seems to contradict this assumption as his moderate summer pruning leaves spurs alone and only removes vegetative wood.  I believe that anything that sends more energy to the roots will increase a tree's vigor.

 

Sometimes the biggest danger of research based information is how it is interpreted.  Actual (and plentiful)  experience in the field can be very helpful to an accurate interpretation.  That's not to say that an extended formal education can't also be helpful- but give us actual practitioners some credit (at least until we start publishing competing books).  All professionals need credibility to make a living.