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30 years of Observing Oaks at Stanford

Articles: 30 years of Observing Oaks at Stanford

Performance of oaks, both existing and test-planted, as determined by former Apple Senior Arborist Dave Muffly. Please see www.oaktopia.org for more information on and photographs of many of the trees listed below.

Quercus cerris, summer foliage. Photo: courtesy of Oaktopia.org
Quercus cerris, summer foliage. Photo: courtesy of Oaktopia.org

Superior Performance

Quercus agrifolia – the most common native tree by far, but narrowly adapted endemic species vulnerable to climate disruption

Q. castaneifolia – potent, large oaks that need to be selected for growth habit and clean winter leaf drop

Q. cerris – selected for aphid-resistant taxa and clean winter leaf drop

Q. engelmannii – consistent performance of species and taxa, moderate size, generally upright growth, climate change adaptive replacement for both Q. agrifolia and locally-faltering Q. douglasii

Q. lobata – must be nursery selected for powdery mildew resistance and growth habit in nursery

Q. macrocarpa – close relative to Q. lobata, must be selected for powdery mildew resistance, bewildering array of taxa

Q. trojana – smaller, highly drought resistant oak with upright growth habit, but can make large acorns

Good Performance

Quercus calliprinos – handles harshest conditions, viciously spiny leaves, shrubby growth, pure form requires excellent soil drainage

Q. canbyi – promising moderate size oak with attractive winter color, not for harsh sites

Q. gambelii – closest natural relative to Q. lobata but smaller, must be selected for powdery mildew resistance

Q. shumardii – must be selected in nursery for clean winter leaf drop, oversize basal flare

Q. polymorpha – late fall new growth often killed by low temperatures, variable winter leaf drop

Adequate Performance

Quercus nigra – variable chlorosis resistance, weak branch attachments, slow growth, lack of drought resistance

Q. coccinea – hold dead leaves in winter until maturity, oversize basal flare, lack of drought resistance

Variable Performance

Quercus ithaburensis – true Q. ithaburensis is a solid performer, but most available seed is hybridized and variable

Q. lobata – staggering variability in powdery mildew resistance and growth habit, with good trees fantastic and bad ones tragic

Compromised Performance

Quercus robur – sooty mold on all specimens observed throughout Bay Area

Q. robur ‘Fastigiata’ – controversial growth habit, hold dead leaves in winter

Q. ×sargentii – hybrid with Q. robur. Good growth but consistent sooty mold

Q. douglasii – incessant powdery mildew, highly compromised growth, natural seedlings rare

Q. kelloggii – exhibit a wide variety of leaf diseases when grown outside native range

Q. chrysolepsis – not a survivor species on valley floor – all historical specimens planted died young

Q. palustris – prone to severe chlorosis, hold dead leaves in winter, typically very short-lived

Q. turbinella hybrids – prone to severe powdery mildew





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