10780Alderbrook_SA P
ARBORIST REPORT
Com unlit", Amen 'Department
RE: OAK CONDITION ASSESSMENT PI �APjkk
n — Cupertino
CUPERTINO kI�D
JUNE 10, 2020 Case# n1gu Qgn2souFa & si PREPARED FOR: Approval � ` iy # 2008
JILL H A L L O R A N Approval Date 09/17/20
10780 ALDERBROOK LN Signature Jeffrey Tsumura
CUPERTINO, CA 95014
Case Manager
ASSIGNMENT
On June 3rd of this year, at the request of the property owner, I visited 10780 Alderbrook Lane.
The purpose was to assess the condition of a coast live oak tree in their front yard, and make a
recommendation for continued care, or removal. This report may be submitted to the City to
obtain permits. Photos of the tree can be found at the end of this report.
FINDINGS
I identified the tree as a mature coast live oak(Quercus agrifolia). I measured the trunk diameter
at 25.5 inches (4.5 feet above grade). The tree was approximately 60 feet tall with a canopy
spread of 40 feet (See Photo A). It was located between the driveway and the property line in an
unirrigated strip with ivy as groundcover. There was a pine tree also planted in the strip. The
front lawn on the other side of the driveway from the oak received year-round irrigation.
The tree, which was "evergreen," was completely browned. The cambium of the trunk appeared
to be dead all the way around, from the ground level to about a six-foot height. The bark and
outer wood had a bulged, cracked surface (See Photo B). Holes in the bark and frass at the base
of the tree were characteristic of beetle infestation. There were also some black bubble-shaped
fungus growing from a few cracks in the dead bark, which I identified as Hypoxylon canker, a
secondary fungus that can weaken the structure of already diseased or dying trees (Photo Q. I
used a chisel and mallet to expose underneath the bark, and the tissues were brown and dead
I I 1 BO FIRESTONE CONSULTING&DESIGN
BUSARA FIRESTONE,CERTIFIED ARBORIST#WE-8525A
1755 YOSEMITE DR.,MILPITAS,CA 95035 asG,,..qI
E: BUSARA@BOFIRESTONE.COM P:(408)497-7158 A M E R I C A N SOCIETY of
# # WWW.BOFIRESTONE.COM CONSULTING ARBORISTS
10780 Alderbrook Ln.• Halloran • 06/10/20
Co m m GW tVoDtVe4dpm?rert 0e pa rt me nt
Planning Divisi9Sbu-2QMpertino
{UPERTMO APPROVED
(Photo D). I saw no signs of other fungal fruiting bodies orCTy&e#um that wou1�4020_08qoot
fungus, nor did the tree did not have a bleeding canker consistent with symptomsti 6 &D(s)
Approval Body: Director/Staff
Reportedly, the tree's canopy had appeared healthy the revlous a . Thgogyp �r� decline of
pproval a e
the tree's overall appearance happened just this spring. the property owners texted me later
the same week to notify me that the mimosa tree in their r n£yar�had r®rnXU'Te=re Tsumura, ,_ _Case anager
City worker said the tree had "white rot." I was not able to conduct an inspection before the
debris was removed.
CONCLUSION
Although lab testing would be required to confirm the presence of specific pathogens, the oak
tree in the Hallorans' front yard had symptoms characteristic of advanced root rot. From my
observations of the tree and site conditions as well as the history of another mature tree failing
at the site, I suspected Phytopthera root rot. The pathogen was likely introduced by nursery
stock, and thrived in the conditions of the irrigated lawn. Coast live oak have a reduced lifespan
and can fall prey to root rots when receiving year-round irrigation. Hypoxylon canker was also
found on the tree infecting the dead trunk tissues as a secondary host. Bark beetles had also
infested the tree, a secondary pest resulting from the tree's compromised defenses and
abundant access to water.
Disease agents had caused extensive damage to the roots and vascular system as to prevent
flow of water into the canopy, and death of the above ground parts of the tree followed suit.
It was my assessment that the tree had recently died, and that no treatment could restore it
to health. Therefore, I recommended removal and replacement with a tree more suited to
the site conditions, as the most reasonable course of action.
PREPARED BY: BUSARA FIRESTONE
ISA-CERTIFIED ARBORIST#WE-8525A
WWW.BOFIRESTONE.COM
10780 Alderbrook Ln.• Halloran • 06/10/20
Co m m 0W tVoD4iVe4dpm?rert 0e pa rt me nt
Planning Divisi9Sju-fMpertino
CUPERTINO APPROVED
RECOMMENDATIONS case# TR-2020-032
---Apptiratiun-Nurnber(s)
Approval Body: Director/Staff
In my professional opinion, the tree was dead and that no f eaomaeikctueld r o health.
"ffy/�
Therefore, I recommended removal and replacement. Re of of tfie tree would oe justiried
Si nature ,,,__ Jeffre�,Tsymura „
by Cupertino municipal code 14.18.180 clause A.1, as the �'ee was „r4&Lr;TQ'-Wrseas
Case Manager
In my assessment, there was space for replacement plantings of one or two shade trees. Trees
may be planted in the same area as the existing tree, or in the front yard at least 10 feet from
the building and six feet (6') from pavement. Many native species would not be suitable in
these site conditions, as most are adapted to receive water only during the cool season.
Species suggestions are not limited to but include the following, which are plants thought to
have some resistance to Phytopthera:
Ginkgo (Ginkgo biloba)
Japanese pagoda (Styphnolobium japonica)
Dawn redwood (Metasequoia glyptostroboides)
River birch (Betula nigra 'Heritage' or 'Duraheat')
If the parties involved have any questions on the assessments provided in this report, please
feel free to contact me.
Sincerely,
Bo Firestone
ISA-Certified Arborist WE-#8525A I ISA Tree Risk Assessor Qualified I ASCA Tree and Plant Appraisal
Qualification I Member,American Society of Consulting Arborists I busara@bofirestone.com (408)497-7158
PREPARED BY: BUSARA FIRESTONE
ISA-CERTIFIED ARBORIST#WE-8525A
WWW.BOFIRESTONE.COM
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