Pine-oak rust

Cronartium quercuum

Cronartium quercuum (the Pine-oak rust) is a fungus causing damage to both Pine trees (Pinus) and broad leafed trees in the family Fagaceae, most notably Oak (Quercus).
Cronartium quercuum This is a picture of Cronartium quercuum infecting a Virginia Pine tree at the Mckeldin Area of Patapsco Valley State Park in Carroll County, Maryland. Cronartium quercuum,Geotagged,Pine-oak rust,Spring,United States

Appearance

The infections by this rust fungus cause large spindle-shaped galls on the points of infection, mostly on the branches and stems of the trees. Trees under 10 years old are usually affected most, but it may also make older trees vulnerable to the point of breaking in heavy storms.
Cronartium quercuum This is a picture of Cronartium quercuum at Kinder Farm Park in Millersville, Maryland. Cronartium quercuum,Geotagged,Pine-oak rust,United States,Winter

Distribution

This fungus has a holeartic distribution, south to Central America and Southeast Asia.

References:

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https://www.cabi.org/isc/datasheet/16153
Taxonomy
KingdomFungi
DivisionBasidiomycota
ClassPucciniomycetes
OrderPucciniales
FamilyCronartiaceae
GenusCronartium
SpeciesCronartium quercuum
Photographed in
United States of America