MELAMPSORA 



325 



Pine branch twist. The aecidium phase of Melampsora 

 pinitorqua, Rostrup (= Caeoma pinitorqiaim, A. Br.), has been 

 shown by Hartig to be very destructive to young pines, 

 seedlings being sometimes diseased as they appear above 

 ground. About the age of thirteen the disease dies out, and 

 those that have not been too severely attacked, recover. 

 Plants that are attacked when quite young are usually killed, 



&>th^ 4 



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Fig. 98. Melampsora pinitorqua. 1, top of young pine attacked by the 

 aecidium stage ; 2, two chains of aecidiospores ; 3, aspen leaf with sori of 

 teleutospores ; 4, section of cushion of teleutospores, still covered by the 

 epidermis. Figs. 1 and 3 nat. size ; remainder mag. 



as the fungus appears year after year if damp weather prevails 

 in May and June ; this indicates that the fungus is peren- 

 nial in the tissues of the host. 



In the seed-bed or young plantation the disease usually 

 spreads from a centre, due to infection by wind-borne spores, 

 showing that the aecidiospore stage is capable of perpetuat- 

 ing the disease, without the intervention of another condi- 

 tion of the fungus. Spermogonia and aecidia appear on the 



