242 The Philippine Journal of Science ms 



Causal organism. — The minute black specks produced in the 

 diseased parts are pycnidia. They are dark brown, spherical, 

 and contain a mass of one-celled, somewhat elongated, olivaceous 

 spores. In pure culture, at first, a growth of white mycelium 

 develops. Later this white mass changes into a dotted mass of 

 black pycnidia. Characteristic diseased lesions may be produced 

 by inoculation with a pure culture. 



Control. — The most important control consists in the destruc- 

 tion by burning of all the diseased leaves and fruit followed by 

 crop rotation. If severe cases of infection have been experi- 

 enced, more drastic control measures must be practiced. These 

 consist in the treatment of seed with formalin, 1 to 2 per cent 

 for fifteen minutes, dipping of seedlings in Bordeaux mixture 

 or a weak solution of copper sulphate before planting, and 

 finally by spraying with Bordeaux mixture at intervals of from 

 two weeks to one month. 



LEAF spot: sakcinella raimundoi saccardo 



Symptoms. — A leaf spot frequently found on dying leaves of 

 eggplant, but doing little damage. Small irregular blackish 

 spots are produced on the surface of dying leaves. Diplodina 

 degenerans Diedicke and Phoma solanophila Oud. are found on 

 decaying fruit. 



SOLANUM TUBEROSUM LINN. POTATO 



BACTERIAL WILT: BACILLUS SOLANACEARUM ERW. SMITH 



Symptoms. — The common bacterial wilt of solanaceous plants 

 is particularly severe on potatoes, often limiting their produc- 

 tion. The Irish potato is not acclimatized in this country except 

 in the higher altitudes; consequently in its weakened condition 

 it is subject to the attacks of soil bacteria. 



Diseased plants first wilt and then fall over. In advanced 

 cases the lower portion of the stem may be discolored. The 

 stem end of diseased tubers, when sectioned, shows a blackened 

 ring in the vicinity of the vascular bundles just below the sur- 

 face. In advanced stages the tuber rots. In severe cases the 

 entire crop may be destroyed. 



Causal organism. — The organism producing this disease is 

 the same as that attacking other solanaceous plants. The wilt- 

 ing is produced by the bacteria clogging up the vascular bundles. 

 The bacteria pass from the vascular system of the stem into 



