Guy,
Great thoughts, so thanks.
There are so many problems with studying mature trees (like how to compare results with a control group, when most mature trees vary significantly from each other). So, the work does not get done, by and large. But if you spend decades practicing some technique or another, and compare how your trees fare with how others nearby do, you start to arrive at "truth" in a less rigorous, but as valuable a way. Especially if you get a chance to dissect some wood from the trees you've pruned, to compare to that of the neighbor's.
Just because the scientific study hasn't been done does not necessarily mean that some people, if they are serious and conscientious, don't know for an absolute fact that a particular technique is or isn't effective (sorry about the quadrupal negative). A good example is the fact that topping has been shunned in some cultures for centuries, even though the work of proving it's inadvisability wasn't done until later. Some people cared enough, and were observant enough, that they just knew it was wrong. Another (and I think Cass comes out on the wrong side of this one) is pollarding. This technique has been used for centuries, but it wasn't until lately that it was shown via experimental method to clearly not cause significant decay, while preventing massive failure.
Where, btw, is the peer reviewed work relating to her phrase "tree dignity"? Some rounded over crab apples around my town look amazingly dignified to me.
Back to the tree in question: The homeowner did mention that he watered the heck out of the tree during last years drought, which agrees with the causal conditions described in SL for phythopthora.
Pictures of the tree: I need hardware, so I can load my software to process any images. I'm probably a week or two from getting this together, so I'll revisit this thread when I can post the pics, (sans teenager, I think
)