XIII, A. 5 Reinking: Philippine Economic-Plant Diseases 



239 



tings should be made only from healthy canes. All diseased 

 plants should be dug up and burned. After the cane has been 

 cut in diseased fields, these fields should be burned over. In se- 

 verely infested sections of Java, healthy cuttings are obtained 

 for plantings from fields that have been planted at an elevation 

 of 610 meters. Conditions at this elevation are such that per- 

 fectly healthy and vigorous canes are produced. At the age 

 of 6 months such canes are used for cuttings. This is done to 

 avoid all possibilities of deterioration of the cane. It does not 

 appear that such methods are necessary as yet for plantations 

 in the Philippines. Sanitation measures, such as burning over 

 diseased fields after digging up and burning all diseased plants 

 along with the strict selection of cuttings from healthy, vigorous 

 plants, ought to hold the disease in check. 



The grovi'th of resistant varieties will also aid in controlling 

 the disease. 



smut: ustilago sacchari rabenhorst 



Symptoms. — This is a smut that seems to be epidemic in its 

 attacks. During seasons favorable to its growth much damage 

 has been done. The disease does only slight damage in 

 well-kept plantations. The tips of young shoots are more 

 usually , attacked. They develop into long, slender, curved, 

 shrunken, dusty, blackened 

 masses. These shoots are often 

 from 30 to 60 centimeters in 

 length and are covered with 

 spores. The diseased portion 

 may extend downward in the 

 shoot inside the mass of leaf 

 sheaths (Plate XVII, fig. 1). 



The disease also occurs, often 

 in abundance, on the wild sugar 

 cane, Saccharum spontaneum 

 Linn. 



Causal organism. — Spores are 

 single-celled, spherical, smooth, 

 and dark brown. They ger- 

 minate readily in water overnight, producing a hyaline promy- 

 celium with elongate hyaline sporidia. The promycelium is 

 frequently branched (fig. 32). 



Control. — Strict sanitation methods consisting in the destruc- 

 tion, by burning, of all infected portions should be practiced. 

 All diseased material found on wild sugar cane also should be 



Fig. 32. Ustilago sacchari Rabh. a, spores 

 (X 340) ; 6, germinating spores 

 . with promycelia (X 340) ; e, 



sporidia (X 340). 



