Spruce and Fir Broom Rusts

Chrysomyxa arctostaphyli Diet., Melampsorella caryophyllacearum Schroet.

From: Field Guide to Diseases and Insect Pests of Idaho and Montana Forests, USDA Forest Service Northern Region, Publication Number R1-89-54

Hosts. – Engelmann spruce – Chrysomyxa arctostaphyli.
Alternate host. – Kinnikinnick (Arctostaphylos uva-ursi).

Grand and subalpine firs – Melampsorella caryophyllacearum
Alternate host. – Chickweeds (Stellaria spp. and Cerastium spp.)

Distribution. – Occasional throughout range of hosts in Idaho and Montana.

Damage. – Witches brooms are formed on infected branches. Growth loss may occur under conditions of severe infection. Form is sometimes affected by large brooms.

Identification. – Dense witches brooms with stunted, yellow needles readily identify these diseases (fig. 83). The needles are shed in fall, giving the broom the appearance of being dead during the winter. New, chlorotic foliage develops in spring and the fungus sporulates in early summer. Pustules or tongues of yellow or orange spores erupt through the leaf surface (fig. 84).

	Image Unavailable
Figure 83 - Fir Broom Rust witches brooms.	Figure 84 - Sporulating Yellow Witches Broom.

Similar damages. – Other species of leaf rust fungi are occasionally en- countered on spruce and true firs. While the fruiting appears similar, these fungi do not cause witches brooms.

Link to Spruce Broom Rust Images in Forestry Images

Link to Fir Broom Rust Images in Forestry Images

References.

Anonymous. 1982. For. Insect & disease identification and management. USDA For. Serv.,Northern Region; Idaho Dept. of Lands, Insect and Disease Control; Montana Dept. of State Lands, Division of Forestry. 192 p.

Bega, R. V. 1978. Diseases of Pacific Coast conifers. USDA For. Serv. Ag. Hndbk. No. 521, 206 p.

Boyce, J. S. 1961. Forest Pathology. McGraw-Hill Book Co., New York, NY. 572 p.

Hepting, G. E. 1971. Diseases of forest and shade trees of the United States. USDA For. Serv. Ag. Hndbk. No. 386, 658 p.

Peterson, R. W. 1964. Fir broom rust. USDA For. Serv., For. Pest Leaflet 87, 7 p.

Ziller, W. G. 1974. The tree rusts of western Canada. Can. For. Serv., Publ. No.1329, Dept. of the Env., Victoria, B.C. 272 p.

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