180 MANUAL OF TREE DISEASES 



Brown-Mold Leaf-Blight 



Caused by Rosellinia sp. ? 



The importance and prevalence of this disease of hemlock 

 is so far not known. It has been found in North Carolina. 

 The needles of the lower branches become yellow. The af- 

 fected twigs show a growth of yellowish-brown or grayish 

 mycelium covering the bark and investing the bases of the 

 yellow needles. The dead needles either fall off or are held 

 by the tangle of mycelium. Small dome-shaped fruiting- 

 bodies of the fungus are found slightly sunken in the mycelium. 

 Although not definitely determined, this fungus apparently 

 belongs to the genus Rosellinia. It has not yet been definitely 

 established that the brown mycelium is directly responsible 

 for the diseased condition. 



Reference 



Graves, A. H. Notes on the diseases of trees in the southern Appa- 

 lachians III. Phytopathology 4 : 63-72, pi. 5, fig. 1-10. 1914. 



Leaf and Cone Blister-Rusts 



Caused by Pv^ciniastrum minimum (Sehw.) Arthur, and P. myriiUi 

 (Schum.) Arthur 



Two species of the blister-rust fungi attack the green parts 

 of the eastern and Carolina hemlock. These rusts are very 

 similar in appearance and have been found in widely separated 

 localities throughout the range of the two eastern hemlocks. 

 The leaves and cones may be at times so heavily infected 

 that the leaves fall and the cones fail to mature viable seeds. 

 This happens only in the case of individual trees which stand 

 close to the alternate host plants which these fungi require for 

 the completion of their life history. 



