Ed
I was taught to prune the "shigo" method with the branch collar intact and the resultant wound is 105% of branch diameter instead of the conventional way witch results in a wound 135% of branch diameter (different species different percentages obviously)
"All those large cuts exposed apoplast. The symplast has chemicals in place to perform compartmentalization and wall off the cut area. The apoplast is a sitting duck for infection"
I found this interesting as I had not had this explained to me before.
I along with everyone else have noticed cuts producing "sap"
I have had to do a fair amount of cut stump poisoning of Ziziphus mauritiana
http://www.dpi.qld.gov.au/documents/Biosecurity_EnvironmentalPests/IPA-Chinee-Apple-PP26.pdf
The herbicide needs to be applied within 15 seconds or it will not work, the explanation was that the wound would be come covered in a waxy substance.
On reflection I think a better explanation was that Phloem flow would not draw the herbicide in and allow it to be translocated and that any xylem flow would dilute the herbicide with latex, resins or mucilage.
All of that had me assuming there was some amount of protective "sap" over the properly done cut while the cambium roll was forming over the wound.
Anyway I spent many hours today reading about "apoplast" and "symplast"
and anything that looked reputable about tree wounds including a comparison of wounds that concluded that larger wounds heal at a faster rate than smaller wounds i.e. the cambium roll was forming faster after tree diameter and growth rates were accounted for, it also concluded that slower growing species more completely covered the wound with a cambium roll than faster growing species that may never form a complete cambium roll. Another article about auxin gradients around wounds, might be a clue to why this happens.
From a simple risk assessment
reduce the hazard, use good hygienic cultural practices
reduce the exposure, minimise the wound size
You have convinced me topping is bad, much worse than I thought
I plead guilty to being seduced by pictures of an oak tree that is still alive after being pollarded since medieval times, truth be known it is probably the only one left out of what was once a very large grove of oak trees.
Ed do you have a link for "apoplast" and "symplast" and the chemicals involved in compartmentalization that you think I should read?
I would like to understand this more. I was happy that I understood photosynthesise better after I read the Calvin–Benson cycle a couple of times
