Fir broom rust, Melampsorella caryophyllacearum
 

Fig. 222  Discoloured upright broom.	Fig. 223  Typical short, yellow, infected needles found on brooms.

Distribution:  Throughout the host range in B.C. 

Host Susceptibility:  Amabilis fir, grand fir, and sub-alpine fir are the major hosts. An alternate host is chickweed.

Signs & Symptoms: Distinctive, greenish-yellow, upright brooms are visible in summer. The colour of these brooms contrasts with the strong green of healthy needles on the same tree. Broom needles are pale yellow, shorter and thicker than normal needles, and are arranged in a spiral. In summer, the underside of these needles are covered with blisters filled with yellow or orange spores. The broom needles are cast in the fall and a new flush appears in the spring. At the base of the broom, infected branches and stems are swollen, forming a canker or a gall.

Damage: In British Columbia damage has been light; however, volume loss, growth reduction, and mortality can occur as a result of this disease. Volume loss results from trunk swellings, cankers, and spike-tops. Growth reduction results from decreased productive crowns, and direct mortality may result from excessive numbers of brooms. Indirect mortality may result from attacks by secondary insects or wind breakage at or near a broom. 

Can Be Confused With: The brooms and swellings caused by fir broom rust could be confused with mistletoe infections or genetic abnormalities. However, the chlorotic needles in the summer and complete loss of needles in the winter identify fir broom rust. True firs are seldom infected by dwarf mistletoes, and needles on a dwarf mistletoe broom remain green.

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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 March 04, 2002