Fir Needle Cast, Blight, and Rusts
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Contents |
Hosts
Grand fir and subalpine fir.
Distribution
Range of hosts in Idaho and Montana.
Damage
Needles are killed within 1 or 2 years of infection. Severe infections may reduce growth. Christmas trees are often severely degraded by needle diseases.
Identification
The general pattern of occurrence of needle cast, blight, and rusts is that the greatest infection occurs low in the crown. A single year's complement of needles is usually most severely infected at a time (fig. 111). Chronic infections leave trees with thin crowns and dead lower branches.
Similar damages
Shoot blight by Delphinella balsamea kills current year's needles as well as new shoots. Winter desiccation appears somewhat similar but foliage in the upper crown is usually more damaged than that in the lower crown.
References
Bega, R. V. 1978. Diseases of Pacific Coast conifers. USDA For. Serv. Ag. Hndbk. No. 521, 206 p.
Funk, A. 1985. Foliar fungi of western trees. Canadian Forestry Service, Pacific Forest Research Centre BC-X-265, 159 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
