FIR DISEASES 157 



prove that they should be reduced to- one species with racial 

 differences as to the fern hosts preferred. 



A very similar blister-rust of the second-year needles occurs 

 in the northwestern states on Alpine and grand fir and has 

 been found to be due to Uredinopsis pteridis Weir and Hubert 

 on species of Pteridium. The life history of this species is 

 different from those above mentioned in that the teliospores 

 do not over-winter. The basidiospores form in late summer 

 but the fir needles infected in the autumn do not show the 

 white blisters until ea,rly the following spring. 



In the other species the young newly formed needles are 

 infected in the spring by basidiospores from over-wintered 

 teliospores, and the white blisters are formed later in the same 

 season. On the fern leaves the urediniospores show as yellow 

 or brownish rust-§pots. 



Fireweed rust. 



Another of the white blister-rusts occurring to some extent 

 on fir needles in this country as well as in Europe is caused by 

 Pucciniastrum pustidatum (Pers.) Dietel. This pathogene 

 has its m-edinial and telial stages on species of Epilobium, es- 

 pecially E. angustifolium, the great willow-herb or fireweed. 

 Although the fungus occurs on several species of Epilobium, 

 teliospores are known certainly to occur only on E. angiisti- 

 folium. 



Blueberry rust. 



A common blister-rrust of fir needles in Europe is caused by 

 Calyptospora columnaris (Alb. and Schw.) Kiihn. It has its 

 alternate stages on species of Vaccinium. On these latter 

 plants the stems are attacked and become swollen. The in- 

 fected stems grow erect and become much taller than sur- 

 rounding bushes. The stems are at first reddish and later 

 become brown or black. The teliospores are formed in the 



