I have a 3 year old pin oak which has shown some strange growth related
trunk and limb damage. A local nursery (Pike's) said I should trim the
branches in the spring if they then don't produce leaves. Here are the
I believe it's even gotten much worse since Aug 28th when these
pictures were taken. I live right outside Atlanta, Ga and we've gotten
TONS of rain this year.
Should I just prune these branches right away? Is there harm in
waiting until the spring and seeing if they can be salvaged? I
absolutely love this tree and I planted it myself, I get so many
comments on how beautiful it is.
Cracked bark can be caused by growth spurts; a small amount of such
cracking would not be unhealthy. It can also be caused by rapid freezing &
thawing, which need not be a threat to the tree's overall health. Cracking
can also go deep into the wood, structural damage caused by wind or being
knocked into by other trees that were felled against it, or started from
shrinkage during drought. A tree can live quite healthily with such cracks
but will be more susceptible to blow down when it gets really large, plus
the cracks can provide ingress to borers or sap eaters, or permit pockets
Pin oaks are susceptible to canker diseases Phytophthora or
Botryosphaeria, pretty much untreatable especially when it shows on the
trunk & can't be trimmed out; but if there is no attendant oozing of
darkened resins, and/or branch tip-death, it is not likely such a
pathogen. Trees ill from wilt fungus will also exude copious amounts of
sap; many leaves will show "half leaf syndrome" drying out on one side of
a leaf only; with severe summer bronzing of leaves; & you may detect a
fruity smell from the crack which is the wilt fungus's odor. In areas
where oak wilt is prevalent, sap-eating beetles enter these cracks & track
in fungus that causes overall wilt & death.
There are sap-depleting pests such as scale which can cause bark cracking,
also with stunted, yellowing, or dead leaves, & overall tree weakness.
Wood-eating borer infestations can also cause it, but you would be able to
spot the exit-holes.
Sick trees will often have a really great year of producing excessive
numbers of acorns trying to reproduce before dying.
But there's every chance the tree is not having any actual problem but is
just outgrowing its outer layer of bark & callousing over the cracks. You
need to first establish a specific pest or pathogen before treating a
tree, & if there is no problem, but only growth causing bark cracking, you
wouldn't want to stress the tree with any unecessary treatments of any
kind. It might be worth an hour of an arborist's time to get it right; an
arborist can cause about $100 for one hour of help & you'd get a good
prescription for ongoing care far more reliable than what some random
nursery owner or worker guessed.
If pruning is all that is called for, the best time is mid-summer or early
to mid winter; spring or autumn pruning will further injure a stressed
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