DANGEROUS INTERNATIONAL FOREST TREE DISEASES 81 



later through ascospores. The attack is, however, not visible to the 

 eye until the spring, when the snow on the plants melts away and 

 they are exposed to the direct influence of the light. The damage is 

 first noticed as brown spots on the shoot inside the needle base. The 

 needles will then get characteristically brown from inside out towards 

 their points, and finally the needles as well as the buds and the whole 

 shoot will die. 



The fungus seems to be a weak parasite that needs specially favor- 

 able conditions to spread epidemically. The reason for its occurrence 

 in such a large scale in 1958 and the years after, not only in nurseries 

 but also on pine heaths in upper Norrland, was probably the heavy 

 thaw in February in 1958, by which the plants were directly damaged 

 in the compact layer of ice that was left when the cold set in again in 

 March the same year. Another important factor was that the plants 

 evaporated water, which could not be replaced through the roots in the 

 frozen ground. 



Hosts : 



Picea excelsa 



Pinus sylvestris 



P. nigra 



P. contorta var. latifolia 



P. montana 



P. laricio var. austriaca 



P. cembra 



Pseudotsuga taxifolia (Kujala 1950) 



Literature : 



Gremmen, J. Some additional notes on Crumenula de Not. and 



Scleroderris de Not. Sydowia Ann. Mycol. 1955. 1955. 

 Kujala, V. Uber die Kleinpilze der Koniferen in Finnland. Com- 



mun. Inst. Forest. Fenniae 38 : 4. 1950. 

 Lagerberg, T. Granens topptorka. Medd. Stat. Skogsfors. anst. 



10. 1913. 

 van Vloten, H., and Gremmen, J. Studies in the Discomycete genera 



Crumenul-a de Not. & Cenangium Fr. Acta Bot. Neerlandica 2 



(2). 1953. 



