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Western gall rust, Endocronartium harknessii,
 

Fig. 169
Infections on stems of young trees often result in hip cankers as the trees grow.
Fig. 170
Symptoms resulting from complete girdling.
Fig. 171
Lodgepole pine with multiple galls.
Fig. 172
Old stem gall. Note rough surface of bark.

Distribution: Throughout B.C.

Host Susceptibility: Highly susceptible species are lodgepole and ponderosa pine.

Signs & Symptoms: Western gall rust produces round woody swellings on stems and branches. Orange spores are produced on galls in late spring. These spores directly infect other pines through elongating leaders and branch shoots. Suitable climatic conditions that occur every few years result in "wave years" of infection. The fungus is an obligate parasite and remains alive as long as the host branch or stem. However, infections stop releasing spores after about age 10. Most stem infections occur below a height of 3 m. Hip cankers result in distorted growth from partial stem girdling. Infected bark can be fed upon by squirrels. 

Damage: Western gall rust is very common throughout the range of lodgepole pine. Stem galls often lead to mortality either through girdling or through stem breakage. Branch galls do not cause serious harm. The disease is usually more evenly distributed throughout stands than blister rusts, which require an alternate host.

Can Be Confused With: Small galls can be confused with Comandra infections, particularly when spores are present. Gall rust produces distinct woody swellings while blister rusts do not.

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Contact Tim Ebata if you have comments on the presentation of this information.

BC Ministry of Forests
Forest Practices Branch
P.O. Box 9513 Stn. Prov. Gov.
Victoria, BC
V8W 9C2

Section phone: (250) 387-8739
Section fax: (250) 387-2136


Last updated February 18, 2002