Figures 1-7. The selection and preparation of 



healthy and parasitized conifer explants for 

 tissue culture. Figures 1 and 2, the type 

 of stems found most suitable for tissue 

 culture explants of healthy and infected 

 western white pine and other conifer species. 

 Arrow denotes the discolored edge of the 

 rust-infected zone in figure 2 (2.5X). 

 Figure 2- to 3-cm. sections of healthy 

 (lower) and rust-infected (upper) current- 

 year stems of western white pine prepared 

 for sterilization (2X). Figures 4^ 5j 6j 

 and 7 J stepwise removal of an infected 

 cambium strip from western white pine, after 

 surface sterilization (3/4X). 



