XIII, A. 4 Reinking: Philippine Economic-Plant Diseases 209 



disease may spread to the stem, causing a blackened, water- 

 soaked, weakened stem which finally falls over. In some cases, 

 on older seedlings, only blackened blotches are produced. These 

 may run together and girdle the stem, resulting in the falling 

 over of the seedling. 



Causal organism. — The causal organism is a bacterium that 

 produces a yellow pigment in pure culture. It gains entrance 

 into the plant through stomata and injuries. The organism may 

 live over on the seed and lint for at least four months. It may 

 also live in the soil for a considerable period. 



Control. — The chief control consists in killing the organism 

 on the seeds before planting. The seeds should first be delinted 

 in sulphuric acid and then treated in hot water at 72° C. for 

 eighteen minutes. In severe cases of plant infection, spraying 

 with Bordeaux mixture will reduce the number of infected 

 plants. 



rust: kuehneola desmium (b. et br.) sydow [uredo desmium (berk, et 



BR.) fetch] 



Symptoms. — A common leaf rust found at the College of Agri- 

 culture on Gossypium herbaceum Linn, and on Gossypium brasi- 

 liense Macfad. Infected leaves are entirely covered on both 

 surfaces with the minute brownish to black pustules. Little 

 damage is done. 



HEVEA BRASILIENSIS (HBK.) MUELL.-ARG. PARA RUBBER 

 BLACK ROT OF FRUITS: PHYTOPHTHOEA FABERI UAUBLANC 



Symptoms. — Diseased fruits are blackened, with a more or less 

 watery discoloration, and rot upon the tree. The outer layer 

 of the fruit shrivels, splits and dries up without maturing the 

 seeds. Older diseased pods with matured seeds are shrivelled 

 so that the seeds cannot be liberated. The disease is most 

 severe during excessively damp periods and may cause the 

 loss of the entire fruit crop. The fungus often grows from 

 diseased fruits into the twigs causing a die-back. Usually the 

 disease does not advance far down the twig. Diseased fruits 

 serve as a source of infection for the stem canker. 



Causal organism. — The causal organism is the same as dis- 

 cussed under Hevea and cacao canker and the black rot of cacao 

 pods. 



Control. — ^AU diseased fruits should be collected and burned. 

 Proper distances for planting and the sanitary precautions as 

 discussed under the canker of Para rubber serve equally well 

 in reducing the black rot of the fruits. 



