196 The Philippine Journal of Science 1918 



only present in the parenchymatous tissue, but also that the 

 chief means of spread in the plant is through the vascular system. 

 Xylem tubes in the young leaves and in all portions down to 

 the woody tissue are infected (fig. 10). This accounts for the 

 rapid advance of the disease in the tissue. 



Control. — Trees when once affected never recover. The mode 

 of growth of the palms and the nature of the disease make it 

 impossible to cure trees already infected. The only control so 

 far determined is one of prevention of spread. All diseased 

 trees should be cut down, and the diseased portions should be 

 completely burned or deeply buried after sprinkling with lime. 

 If this precaution of burning all infected trees be carried 

 out under strict supervision, the danger of spread is largely 

 eliminated. 



The greatest factors in the severity of the disease are the 

 growth of coconuts in excessively damp places and in extremely 

 thick plantings. New plantings should be made only in those 

 localities that are best suited for coconut growth and develop- 

 ment. Plantings should not be too thick. The recognized dis- 

 tance for plantings for the best production and at the same 

 time for the best control against bud rot is 10 meters each way.* 

 LEAF spot: exosporium durum saccardo 



Symptoms. — A spot that is not common and causes little dam- 

 age. It is characterized by the production of black tubercular 

 or wartlike bodies, the sporodochia, on the surface of leaves. 

 These spots are scattered, sometimes densely, over the leaf sur- 

 face. In some cases the sporodochia may be surrounded by a 

 light yellowish discoloration of the leaf (Plate VIII, fig. 4) . 



Causal organism. — The wartlike bodies, or sporodochia, have 

 no spines. The conidia are borne on conidiophores and are 

 yellowish to brown and septate. 



Control. — Since the disease is not severe, no special control 

 need be practiced. All fallen diseased leaves should be collected 

 and burned, so as to avoid a spreading or an epidemic. 



LEAF SPOT: PESTALOZZIA PALMARUM COOKE ET GREVILLE 



Symptoms. — This disease is common throughout all coconut 

 regions. As a rule, it is not severe and causes little damage. 

 The vitality of the tree is lowered, and in a few cases, especially 

 on younger trees, the spotting may become severe. Spots often 

 are scattered over the entire leaf surface. Young infections are 

 characterized by small brown to black, elevated, circular spots a 



'See Copeland, E. B., The Coco-nut. London, Macmillan and Co. (1914). 



