XIII, A, 4 Reinking: Philippine Economic-Plant Diseases 



199 



Causal organism. — No organism has as yet been associated 

 with this disease. Consequently no definite control can be given. 



LEAF spot: MICROPELTIS MUCOSA SYDOW 



Symptoms. — A leaf spotting that is found on Coffea excelsa 

 Cheval. and is only of slight importance. Minute, scalelike, 



XJ^-< 



Fig. 12. Micropeltis mucosa Syd. Immature perithecium (X 335). The fungus does not 

 penetrate leaf tissue. 



raised black spots are scattered over the upper and lower leaf 

 surface. They are usually more abundant on the lower surface. 



Causal organism. — T h e s e 

 scalelike black bodies are perl- 

 thecia, within which are borne 

 the asci and ascospores. The 

 asci are clubshaped and contain 

 six to eight hyaline three- or 

 four-celled ascospores. The 

 fungus is a superficial grower 

 and does not penetrate into the 

 leaf tissue (figs. 12 and 13). 



Control. — The disease does 

 little or no damage; consequent- 

 ly no control measures need be 

 practiced. 



Fig. 13. Micropeltis mucosa Syd. 

 with ascospores ( X 340 ) . 



RUST: HEMILEIA VASTATRIX BERKELEY ET BROOME 



Symptoms. — This widely distributed and destructive disease 

 has wiped out the coffee industry in various sections of the 

 Islands. Circular or subcircular orange-red spots cover the 

 under surface of leaves. Infected leaves wilt and drop, repeated 

 attacks causing death to the entire plant. Young spots appear 

 as transparent slightly yellowish discolorations. As the spot 

 becomes older, the yellow increases, until finally a yellow dust, 

 which turns to orange, is produced on the under surface of 

 the leaves. The disease is most severe and evident during the 

 rainy season. 



Coffea arabica Linn., the best commercial coffee in this section, 



