208 



The Philippine Journal of Science 



Pcronoxpnra, on Glycine max 

 (Linn.) Merr. (G. hispida 

 Maxim.), a, portion of typical 

 branched conidiophore ( X 

 320) ; 6, conidia (X 320). 



RUST: TJROMYCES SOJAE SYDOW 



Symptoms. — Frequently soy 

 beans may be severely attacked 

 by this rust fungus. Character- 

 istic brown rust sori are scat- 

 tered thickly on the under sur- 

 face of leaves. Spots are at first 

 circular, raised brown blisters, 

 but later burst open, exposing 

 the spores. The upper surface 

 of diseased leaves is yellowed 

 above the sori on the lower 

 surface. 



Causal organism. — Irregular, 

 short, spiny brown uredospores 

 are produced in the rust sori 

 (fig. 19). 



Control. — Crop rotation 

 should be practiced. 



GOSSYPIUM SPP. COTTON 



ANGULAR LEAF SPOT: BACTERIUM MALVACEARUM ERW. SMITH 



Symptoms. — The disease is present on leaf, stem, and fruit. 

 On the leaf the characteristic spots are from 1 to 4 millimeters 

 in diameter; they are angular, with brownish centers bordered 

 with light brown to yellow. Young spots are smaller and have 

 a water-soaked appearance. They can be more easily detected on 

 the lower surfaces of the leaves. Spots may run together form- 

 ing brownish blotches which later become brittle. The dead 

 brown tissue may fall out of the spots. Badly attacked leaves 

 wither, die, and fall to the ground. The disease may be evident 

 on the tender stalks in the form of blackened cankerous patches. 

 On the bolls, at first, minute water-soaked spots are produced, 

 which later may run together, producing sunken brownish or 

 reddish brown blotches. If the 

 bolls are young when attacked, 

 the contents may be consumed; 

 but on older bolls only the outer 

 layers are invaded, producing lit- 

 tle injury to the fiber. Young 

 seedlings may be attacked first 



, 1 » « 1 ,1 f"'<»- 19- Uro)n yces aojae Syd. 



on the leaf from where the (x sis). 



Uredospores 



