HEMLOCK DISEASES 179 



Control. 



No specific measures of control have been tried, so far as 

 known. The control measures given on page 81 for the shoe- 

 string root-rot may be applied to this disease as well. 



References 



Weir, J. R. Observations on Rhizina inflata. Jour. Agr. Res. 4 : 



93-95, pi. 8. 1915. 

 Hartig, R. Rhizina undulata Fr. the root fungus. In Text-book 



of the diseases of trees, pp. 123-129, figs. 61-70. 1894. 



Leaf-Blight 



Caused by Keithia tsugoe (Farlow) Durand 



The leaves of the eastern hemlock are at times killed by this 

 leaf-blight. Instances are reported in which several trees 

 were almost defoliated. This disease is definitely reported 

 only from New Hampshire, Massachusetts and Wisconsin. 

 ■ It may, however, be found at other places in the range of the 

 hemlock. The leaves that are affected turn brown and fall from 

 the twigs. These symptoms occur in the late summer. The 

 fruiting-bodies of the pathogene form during the summer on the 

 affected leaves; They appear as small black pustules bursting 

 through the leaf-epidermis. Ascospores are forcibly ejected 

 from these fruiting-bodies during moist weather. Additional 

 facts concerning the life history of this fungus will be found 

 on page 90, where a similar disease of western arbor-vitae is 

 discussed. 



References 



Durand, E. J. The genus Keithia. Mycologia 6 : 6-11, pi. 81. 1913. 

 Farlow, W. G. Notes on the cryptogamie flora of the White mountains. 



Appalachia 3 : 245-246. 1883. 

 Spaulding, P. Diseases of the eastern hemlock. Proc. Soc. Amer. 



Foresters 9 : 245-256. 1914. 



