Spruce and Fir Broom Rusts
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Contents |
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).
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.
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.
Field Guide to Diseases and Insect Pests of Idaho and Montana Forests, USDA Forest Service Northern Region, Publication Number R1-89-54
