358 Diseases of Greenhouse Crops 



of the causal organism. Destruction by fire of dis- 

 eased plants and diseased material is recommended. 



Speck Anthracnose 



Caused by Marsonia viola (Pass.) Sacc. 



Symptoms. The presence of the disease is marked 

 by numerous small raised, black or brown colored 

 spots on the upper surface of the leaf (fig. 74, c). 

 The disease, so far as is known, is confined to the 

 leaves, and has not yet proved to be very serious. 

 Jones and Giddings * believe that the disease was 

 probably introduced from Europe with imported 

 cuttings. 



The Organism. Within the minute spots may be 

 found the acervuli in which the spores are borne 

 (fig. 74, b.). The spores are curved and one or 

 two celled. The spetum is generally nearer one of 

 the tips than in the center. 



Control. The disease may be kept in check by 

 spraying with a standard fungicide. 



White Moxd 



Caused by Zygodesmus albidus Ell. and Halst. 



This trouble is generally manifested as a white 

 flourlike coat over the leaves. Little is known of 

 the causal organism, nor has it proven so far of any 

 serious consequence. 



•Jones, L. R., and Giddings, N. J., Vermont Agr. Expt Sta, 

 Nineteenth Ann. Kept: 234-235, 1906. 



