THE PHILIPPINE 



Journal op Science 



A. Chemical and Geological Sciences 

 AND the Industries 



Vol. XIII 



SEPTEMBER, 1918 



No. 5 



PHILIPPINE ECONOMIC-PLANT DISEASES 



By Otto A. Reinking 

 (From the College of Agriculture, Los Banos) 



(Concluded.) 



lycopersicum esculentum mill, tomato 



BACTERIAL WILT: BACILLUS SOLANACEIARUM ERW. SMITH 



This bacterial wilt may be the limiting factor in the produc- 

 tion of tomatoes. It is impossible to grow tomatoes in soil 

 that is thoroughly infected with the organism. 



Symptoms. — The first evi- 

 dence of disease is a wilting of 

 the plant. Later the plant 

 shrivels; it turns yellowish and 

 then brown to black. A dis- 

 coloration of the vascular bun- 

 dles is observed in cross section. 



Causal organism,. — Microspic 

 examination shows the xylem 

 tubes of vascular bundles to be 

 entirely clogged with bacteria, 

 thus stopping the flow of water 

 and causing the wilt (fig. 21). 

 In advanced stages the organism 

 may invade the parenchyma. 



Control. — It is practically im- 

 possible to control the disease 

 in heavily infected soil. Care 

 should be taken to keep the 

 disease-producing organism out 

 of noninfected soil by planting 

 only healthy plants produced 



156257 



Bacillus solanacearum Erw. 

 Smith. Cross section of tomato 

 stem, showing xylem tubes com- 

 pletely filled with bacteria (X 

 350). 



217 



