Spruce and Fir Broom Rusts

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Hagle, S.K; S. Tunnock; K.E. Gibson; and C.J. Gilligan. 1987. Field Guide to Diseases and Insect Pests of Idaho and Montana Forests. U.S. Department of Agriculture, Forest Service. State and Private Forestry, Northern Region. Missoula, Montana. Reprint 1990. Publication Number R1-89-54.

fir broom rust Photo by USDA Forest Service Archive, USDA Forest Service, Bugwood.org Taxonomy Kingdom: Fungi Phylum: Basidiomycota Class: Urediniomycetes Order: Uredinales Family: Pucciniastraceae Genus: Melampsorella Species: caryophyllacearum Scientific Name Melampsorella caryophyllacearum (DC.) J. Schröt

Contents 1 Hosts 2 Alternate host 3 Grand and subalpine firs 4 Alternate host 5 Distribution 6 Damage 7 Identification 8 Similar damages 9 References

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.