xm. A,4 Reinking: Philippine Economic-Plant Diseases 



175 



Causal organism. — Within the 

 sori are produced in abundance 

 one-celled, yellow to brown, usu- 

 ally ovate, spiny uredospores. 

 They may in some cases retain 

 a stalk. Prominent pores are 

 developed. Teleutospores are 

 not produced in such abundance. 

 They may be developed along 

 with uredospores, but usually 

 predominate in sori within 

 which they are found. The 

 teleutospores are two-celled, 

 thick-walled, dark brown, and 

 smooth and usually have a stalk 

 (fig. 3). 



Control. — Crop rotation and the destruction of badly diseased 

 plants should be practiced. 



SOOTY MOLD 



Symptoms. — Frequently a dense sooty mold may be produced 

 on leaves attacked by aphids. The fungus grows superficially, 

 living on the exudate of the aphids. Little injury is done. The 

 fungus has not been identified. 



Didymosphaeria anisomera Sacc. has been identified from 

 languished and dead leaves. On dying leaves, Fumxigo vagans 

 Pers. may be found. Coniosporium sorghi Sacc. is found in 

 dead and decaying stalks. 



ANNONA MURICATA LINN. SOURSOP, GUANABANO 



Puceinia purpurea Cooke, a, te- 

 leutospores (X 315) ; 6, uredo- 

 spores (X 315). 



LEAF SPOT: PHYLLOSTICTA INSULARUM SACCARDO 



Symptoms. — A common and sometimes destructive leaf dis- 

 ease. Spots are irregular and gray to whitish and start at 

 the margins. 



APIUM GRAVEOLENS LINN. CELERY 

 EARLY blight: CERCOSPORA APII fries 



Symptoms. — Irregular roundish spots, which often run to- 

 gether forming blotches, may cover the leaf surface. When 

 young the spots are light brownish, bordered with a yellowing 

 of the leaf. Older spots have ashen gray centers surrounded with 



