216 The Philippine Journal of Science 



bers of sporangiophores and sporangia. The sporangia contain 

 numerous black spores. 



Control. — Sweet potatoes should be stored in a dry, well- 

 aerated place. All rotted potatoes should be destroyed. 



LACTUCA SATIVA LINN. LETTUCE 

 TIPBURN 



Symptoms. — A nonparasitic disease that is common during 

 the dry season. Leaves turn brown at the tip and gradually 

 shrivel up. 



(To be concluded.) 



