the various strains of the host and commented on the influence of the 

 disease upon German silvicultural practices for Douglas-fir. A contro- 

 versy developed on proper control procedures when Geyr (19, 20) 

 opposed both Liese (27) and von Tubeuf (61) on recommended 



methods lor combating the disease. Geyr advocated the location and 

 propagation of resistant strains of Douglas-fir and gradually his 

 views were accepted h\ the others. 



In 1932 Liese (29) compared the susceptibility of the green, blue, 

 and gre) strains of Douglas-fir to the needle cast disease. He con- 

 cluded that the immunity of the green strain was attributable to 

 the late bin sting of the buds, after the infecting ascospores of 

 R. pseudotsugae had been disseminated. He also reported that 

 lammas branches remained healthy clue to their late development. 

 While studying the biology of the fungus, Liese found that twigs 

 with infected needles dried, when cut prior to apothecial maturation 

 (usually April), and ascospores failed to develop. Thus burning was 

 not necessary if severed branches were spread on the ground to 

 facilitate rapid drying. For the practical forester, Liese recommended 

 planting stock from only the fast-growing strains of the coastal or 

 "viridis" varieties of the Douglas-fir 



Rohde (43) reported that the age of infected stands in Germany 

 ranged from 13 to 37 years, but gave the period of greatest suscepti- 

 bility from 15 to 30 years. In the same paper he mentioned one area 

 in northwestern Germany having infected seedlings that were only 

 two vears old. Rohde (44) concluded that mixed stands were as 

 subject to the needle cast disease as pure stands, and that the inci- 

 dence of attack varied greatly with the nature of the season. 



Yon Tubeuf (61) in 1932 briefly summarized the development of 

 the needle cast disease and compared R. pseudotsugae with certain 

 of the Hvstei iaceae. He found only the perfect stage of the fungus, 

 and recommended spraying the voting needles with a Bordeaux mix- 

 ture as a preventative measure. 



A thesis devoted to R. pseudotsugae on Douglas-fir, was published, 

 in part, by Van Vloten (63) in Holland. After unsuccessful attempts 

 to cult in e the fungus on artificial media, he concluded that R. pseu- 

 dotsugae was truly an obligate parasite. He demonstrated that infec- 

 tion took place through the cuticle on either surface of the needle 

 and that onlv the chlorenchyma was invaded. He tra< ed the develop- 

 ment of the apothecia and searched, without success, for the nature 

 of resistance shown by certain blue and grey strains of the host. 



