of the fungus b) ascospores, coupled with the wide dissemination 



of infected nursery Mock resulted in a rapid spread ot the disease 

 over Germans. In a paper on the advance of R. pseudotsugae in 

 Germany, Rohde (45) cited 114 centers of infection by 1934. One 

 center had also been detected in Poland at that time. 



During 1938, the Rhabdocline needle cast disease was reported 

 in Douglas-fir plantations in Holland, Switzerland, Denmark, Nor- 

 way, Sweden, and Czechoslovakia (5). In 1956, Spaulding (54) 

 added Austria, Belgium, France, and Yugoslavia to this list. 



In western North America the fungus is ubiquitous but the extent 

 of its damage has been largely undetermined. Sporadic epidemics in 

 Christmas tree plantations have been reported. In addition to the 

 Pacific Northwest and the Inland Empire, R. pseudotsugae has been 

 reported in Arizona (15), Colorado (52) and the Northeast. In the 

 Northeast, the fungus has become a serious threat in Christmas tree 



ST 



Fig. 2. — Cross-section of a stem of a Douglas-fir infected for five years with R. 

 pseud', go< I he- decrease in annual growth, especially dming the past two 

 years, is readily visible. July 1957. 



19 



