164 



By 1970, the disease had spread throughout the tree's range at lower elevations in 

 Oregon (Kliejunas and Adams 1980). It is easily spread by movement of infested 

 plant stock (landscape plants), including other species of CJtamaayparis. Zobel et aL 

 (1985) conclude that the root disease "probably never would have emerged in epi- 

 demic form without the widespread planting of ornamental Chamaaypans in north 

 western Oregon and Washington." It is also spread through movement of spore-con- 

 taminated soil by machinery and animals. The spores germinate in water-saturated 

 soil. Zobel et at. (1985) estimated that approximately 60 percent of the young regen- 

 eration has been killed by the disease. They concluded that without management 

 techniques, or development of resistant stock, there is a limited future for commer- 

 cial harvesting of Port-Orford-Cedar. 



The restoration and/or preservation of Port-Orford-Cedar has been addressed by sev- 

 eral different approaches. A project to hybridize Port-Orford-Cedar with more resis- 

 tant Chamaecyparis species has been initiated (Roth et aL 1987). Control strategies, such 

 as cleaning soil off of logging equipment, have also been implemented. To minimize 

 the spread of infestation, recommendations have been made for strict management 

 of human and animal (including wildlife) access to Port-Orford-Cedar stands in addi- 

 tion to removing trees proximal to water courses, road edges, and moist sites (Klie- 

 junas and Adams 1980, Zobel et aL 1985). 



Larcti-Poplar Melampsora Rust 



Black Cottonwood (Popuius trichocarpa) and quaking aspen (Populus tnmuloides) are 

 imporunt components of Pacific Northwest forests. These species and various poplar 

 hybrids are planted for fiber and ornamental uses (Newcombe and Chastagner 

 1993a) and are considered as a potential source of biomass for conversion to energy 

 (Abelson 1991). In 1991, rusts were observed in several hybrid poplar plantations in 

 western Washington and Oregon. The rusts were identified as Melampsora medusae 

 f.sp. delloidae, a species endemic to eastern North America, and Melampsora land-pop 

 ultna, a Eurasian rust not previously reported in North America {cf. Newcombe and 

 Chastagner 1993a). By December 1992, M. larid-populina infesutions had been iden- 

 tified in an area about 30 miles wide along the lower Columbia River (Chastagner et al. 



The Tunge oftht black cottonwood u fnm Alaska to loulhtm Califrmia, along the coast arta 



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