DANGEROUS INTERNATIONAL FOREST TREE DISEASES 109 



Range: In North America it is common throughout the range of 

 Douglas-fir in southern British Columbia, Canada, and north- 

 western L T nited States. In Japan it is found in the subalpine 

 forests of Honshu and the primeval forests of Middle Hokkaido. 

 Hosts: Pinaceae — 

 North America : 

 Psevdotsuga memiesii (Mirb.) Franco 

 Abies grandis Lindl. 

 Tsuga heterophylla (Rafn.) Sarg. 

 Pinus monticola Dougl. 

 Abies amabilis (Dougl.) Forbes 

 Abies lasiocarpa (Hook.) Nutt. 

 Pinus ponderosa Laws. 

 Picea sit chensis (Bong.) Carr. 

 Larix occidental-is Nutt. 

 Japan : 



Tsuga diversif cilia (Maxim.) Mast. 

 Abies mariesii Mast. 

 Abies sachalinensis Mast. 

 Picea jezoensis (Sieb. & Zucc.) Carr. 

 Cupressaceae — 



Thuja plicata D. Don 

 Chamaecyparis sp. 

 Literature: 



Aoshima, Kiyowo. Wood-rotting Poria from Japan II. Govt. 



Forest Expt. Sta. Bui. 59, Tokyo. Japan. 1953. 

 Buckland, D. C, Molnar, A. C, and Wallis, G. W. Yellow lam- 

 inated root rot of Douglas-fir. Canad. Jour. Bot. 32 : 69-81. 

 1954. 

 Childs, T. W. Laminated root rot of Douglas-fir. U.S.D.A., 



Forest Service, Forest Pest Leaflet 48. 1960. 

 Mounce, Irene, Bier, J. E., and Nobles, Mildred K. A root-rot of 

 Douglas-fir caused by Poria weirii. Canacl. Jour. Res. C, 18: 

 522-533. 1940. 



Fir Tip Blight 



M. E. Fowler 



Forest Service, U.S. Department of Agriculture, Upper Darby, 



Pennsylvania 



Rehmiellopsis balsameae Waterman is a blight of the current sea- 

 son's needles of several species of fir in Northeastern United States. 

 The disease, which affects all sizes and ages of fir trees, appears first 

 on the lower branches; usually the lateral twigs of these branches are 

 more severely affected than the terminal twigs. Severe infection re- 

 peated for several years may result in the death of small trees; large 

 trees are rarely killed. The disease causes relatively little damage to 

 forest trees but may be very disfiguring and damaging to ornamen- 

 tals. 



Weather conditions exert an important influence on disease sever- 

 ity. A late, moist growing season leads to rapid development of 

 young succulent tissue that is particularly susceptible to infection and 



