SOOTY MOULD OF ORANGE 



101 



Probably no group of fungi are so imperfectly under- 

 stood as the black members of the Perisporiaceae, except- 

 ing the genus Meliola } which has been recently monographed 

 by Gaillard. The sooty mould is probably caused by 

 different species in different countries, as shown by 



Fig. 17. Meliola sp. Sooty mould of orange and citron on 

 orange leaves. 



M'Alpine. In Europe and the United States the disease 

 is generally attributed to Meliola penzigii, Sacc., and M. 

 camelliae, Sacc. Both these are, however, excluded from 

 Meliola by Gaillard, who, however, has not indicated their 

 affinities ; hence it is convenient for the present to use the 



