222 The Philippine Journal of Science isis 



of the causal organism is still in progress, but has not advanced 

 to a stage where a definite name can be given. 



Control. — Abaca should be planted 3 meters apart each way. 

 Plantings in excessively damp, poorly aerated pockets should be 

 avoided. All diseased plants should be cut and destroyed by 

 burning. Care should be taken that the cuts are made well 

 below the advanced portion of the disease. Knives used for 

 cutting should be sterilized after each cut by wiping off with 

 a solution of corrosive sublimate, 1 to 1,000. 



LEAF spot: maceophoma musae (cke.) berl. et voglino 



Symptoms. — This fungus causes a spotting of the leaf similar 

 to that discussed under banana. 



LEAF SPOT: MYCOSPHAERELLA MUSAE SPEGAZZINI 



Sym/ptoms. — Another leaf spot is found on abaca, being similar 

 to that produced by Mycosphaerella musae Speg. on the banana. 

 Spots may be definite and circular, or they may be irregular. 

 The center of each spot is grayish and is bordered by a dark 

 ring. The disease is not serious and causes little damage. 



NICOTIANA TABACUM LINN. TOBACCO 



BACTERIAL BLIGHT 



Symptoms. — A bacterial leaf spot has been observed during 

 the rainy season. Lower leaves are severely attacked. The 

 disease has been evident only during exceptionally moist weather. 

 Spots are irregularly circular, from 5 millimeters to 3 centi- 

 meters in diameter, have brownish gray centers, with watery 

 parchmentlike borders, 3 to 6 millimeters wide. Concentric 

 rings of light and darker brown may be produced in the spots. 

 Smaller spots seem to be limited by the larger veins. Larger 

 spots run together, often covering the entire leaf. In the latter 

 case the leaf is shrunken, somewhat curled, dried up like parch- 

 ment, and opaque. 



Caudal organism. — Isolation experiments indicate that this 

 disease is due to bacteria. Cultural and inoculation studies have 

 not progressed sufficiently to permit the assigning of a name. 



Control. — Plants should not be set too thickly, thus allowing 

 for plenty of air. 



BACTERIAL WILT: BACILLUS SOLAN ACEARUM ERW. SMITH 



Symptoms. — Tobacco may be badly infected with this common 

 bacterial wilt of solanaceous plants (Plate XII, fig. 1). Plants 



