I have a clear recollection from a 5 day workshop with
Shigo in '86 about the dormant bud trace all the way to
pith. I have a much dimmer recollection of a
conversation with him about looking for the bud trace in
an "autopsy" to distinguish the circumstances in which a
particular shoot arose... cannot recall which would be
epicormic or adventitious.
I'm curious about your observations on Populus. I've
just seen a Lombardy poplar with shhots emerging from
soil on both sides of what appears to be the line of 3-4
year old trenching. 1) would you expect to see growth
from a root portion severed from the trunk? 2) would
you expect to see epicormic trunk sprouts in a specimen
infected with the common fungal cankers? TIA for any
observations.
Scott Cullen
--
Scott Cullen
As I understand it, dormant buds form at leaf axils and are connected to the
pith by a bud trace and can remain dormant for the life of the tree.
Adventitious buds form irregularly on older portions of the tree but not in
leaf axils or stem tips and can be deeply embedded or lie close to the
surface of the stem or branch and, unlike dormant buds, have no connection
to the pith. Epicormic shoots form following some sort of trauma such as
pruning or other injury or sudden exposure to light eg following thinning
and I think that this is the point of confusion epicormic shoots are
produced from dormant rather than adventitious buds as is sometimes thought.
Epicormic shoots produce knots in timber and are more of a problem in
angiosperms than gymnosperms. Adventitious buds, as the name suggests, form
in unusual places or out of the normal position eg roots. Aspen, Populus
tremula, is an example of a prolific sucker producer and these suckers are
produced from adventitious buds formed on roots. Therefore, to sum up, as I
understand it, epicormic shoots only arise from dormant and not adventitious
buds. I'm not sure that the term 'epicormic bud' is correct. I think
'epicormic shoot' arising from 'dormant bud' could be nearer the mark.
Maybe it depends on who you've been reading. By the way, I think the
reference could be Harmer 1992.
Hope this adds to the debate
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PRINCIPLES OF TREE HAZARD ASSESSMENT AND MANAGEMENT
WORKSHOP. SILWOOD PARK & WINDSOR GREAT PARK
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June 22nd 23rd 24th Imperial College London's Sillwood Park campus.
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