174 



The Philippine Journal of Science 



Fig. 1. Phyllachora sorghi v. Hohnel. Cross section of stroma, showing perithecium, ostio- 

 lum, asci, and ascospores (X 75). Vascular bundles of leaf develop normally within 

 the mass of fungus mycelium. 



and paraphyses. Sections through the stromata disclose the 

 interesting fact that the vascular bundles of the leaf are not at 

 all injured, for these bundles develop apparently normally with- 

 in the mass of fungus mycelium (fig. 1). The passage of food 

 and water is not inhibited by the fungus, but the vitality of the 

 plant is lowered, for the fungus absorbs food for the develop- 

 ment of its own body and also reduces the chlorophyll area of 

 the leaf. Asci are typical, club-shaped bodies containing usually 

 eight hyaline spores. The ascospores are elongated and gran- 

 ular, with the contents often collected in each end, which in some 

 cases makes them appear two-celled (fig. 2). The paraphyses 

 are slender, hyaline bodies and ai'e produced in abundance. 



Control. — No special control need be practiced. Crop rotation 

 and sanitation will check the disease. 



ilUST: PUCCINIA PURPUREA COOKE 



Symptoms. — Leaves may be 

 entirely covered with rust sori, 

 which lower the vitality of the 

 plants and render them worth- 

 less for forage. Sori are brown- 

 ish, at first closed, later rup- 

 tured, exposing the spores; are 

 raised, elongated, about 1 milli- 

 meter by 2 millimeters, and are 

 frequently surrounded by a dark 

 reddish to purplish discoloration 

 of the leaf surface. Badly in- 

 fected leaves are usually entirely 

 spotted and are nearly covered 

 with a reddish to purplish dis- 

 coloration (Plate I, fig. 2). 



Fig. 2. Phyllachora sorghi v. Hohnel. 

 o, asci with paraphyses (X 

 325) ; 6. aBCOSpores (X 325). 



