XIII, A. 4 Reinking: Philippine Economic-Plant Diseases 201 



therefore, for the Philippines, the best control measure for this 

 variety is spraying. Spraying experiments have shown that 

 the disease can be controlled v^^ith Bordeaux mixture at a cost 

 of 10 centavos ^ a tree per year, 



SOOTY mold: aithaloderma longisetum sydow 



Symptoms. — A black sooty mold may be produced over the 

 surface of leaves. Little injury is done, as the organism is 

 not abundant. 



STEM DISEASE 



No important stem diseases on older plants have been observed. 

 Coniothyrium coffeae Henn. has been found on twigs of Coffea 

 arabica Linn. 



COLOCASIA ESCULENTUM SCHOTT (COLOCASIA ANTIQUORUM 

 SCHOTT) . GABI 



• blight: PHYTOPHTHORA COLOCASIAE RACIBORSKI 



Symptoms. — Gabi, which is extensively grown in the Philip- 

 pines, suffers severely from the attacks of this fungus. Leaf 

 blade, petiole, and corms are attacked. Leaf spots appear at 

 first as small, roundish dark brown spots. They rapidly increase 

 in size, may be circular, oval, or often running together, until 

 finally the entire leaf is diseased. Spots are not confined to the 

 portion of the leaves between main veins, but readily cross the 

 latter. Spots 2 to 3 centimeters in diameter are dark and 

 rather watery and produce drops of a yellow liquid. Older and 

 larger spots have yellowish brown centers bordered by broad 

 watery rings. Frequently the margins have concentric brown 

 or yellow rings (Plate XV, fig. 1). When spots coalesce, cover- 

 ing the entire leaf, a soft, watery, disintegrating leaf is produced. 



In severe cases the petioles may become infected. The fungus 

 gradually invades the petiole, which becomes blackened, shrunken, 

 and watery and finally collapses. The entire diseased leaf then 

 decomposes into a watery mass. 



Infection of the corm may occur in severe attacks and during 

 damp weather. Diseased corms disintegrate with a wet rot. 

 The disease is most severe during the rainy season. 



Causal organism. — A dovniy mass of spores is not produced 

 on the diseased spots, but only a delicate white growth can be 

 detected. This is made up of the conidia produced on short 



^ One peso Philippine currency equals 100 centavos, equals 50 cents United 

 States currency. 



