252 



The Philippine Journal of Science 



Fig. 42. Helminthosporium inconspUuum 

 C. et E. Direct penetration of 

 host tissue (X 325). 



lowish, to gray center, bordered 

 with brown. In the center of 

 old spots is produced a black 

 mold made up of conidiophores 

 and conidia. A black mold is 

 produced on the tassel. 



Catisal organism. — Conidio- 

 phores are brownish and produce 

 large, septate, curved brown 

 conidia (fig. 40). The conidia 

 germinate readily in water, pro- 

 ducing from one to two germ 

 tubes. Conidiophores may also 

 germinate and produce infection 

 (fig. 41). Penetration into the 

 leaf may be either by way of 

 the stomata or by direct penetra- 

 tion into the leaf tissue (figs. 

 42 and 43). 



Control. — Crop rotation should 

 be practiced. Compost made of 



diseased plants should not be put, the same year, upon fields 



to be planted with com. 



Helminthosporium curvulum ^.^-^'^^^ 



Sacc. has been reported from 



the tassels of corn. 



smut: ustilago zeae (beckm.) unger 



Symptoms. — This disease has 

 been reported in the Is- 

 lands. It is characterized by 

 the production of conspicuous 

 black masses on the ear and 

 tassel of com. The disease 

 may be present also on the 

 leaves. These swollen masses 

 are at first covered with a 

 white membrane, which later 

 becomes black, owing to a 

 maturing of the spores. When 

 this membrane breaks, a pow- ^^^ ,3 H.i^^^thosporium inconspicuuv 



dery black mass of spores is C. et. E. Germinating spore 



exposed. ilJlinfr "" ^"" " 



