250 



The Philippine Journal of Science 



condition is a chlorotic one, due to the disappearance of the 

 chlorophyll. On both surfaces of diseased leaves, more abund- 

 ant, however, on the lower surface, a downy appearance is 

 produced by the mass of conidia and conidiophores. At a 

 distance, affected plants look pale. They are stunted and have 

 a bunchy growth, due to the checking of growth and fre- 

 quently a shortening of the internodes. Such plants produce 

 the male inflorescence prematurely. As a rule, no grain is 

 produced. Badly diseased plants wither and die before the 



normal plants are ready for har- 

 vest. In severe cases of infec- 

 tion from 60 to 70 per cent of 

 the crop may be destroyed. 



The disease has also been ob- 

 served on teosinte, Reana luxn- 

 rians Dur. 



Caitsal organism. — Conidio- 

 phores and conidia are hyaline. 

 Conidiophores are thick, short, 

 unbranched at the base, with 

 short branches near the tip. 

 They are produced in abun- 

 dance, arising from the stomata 

 (fig. 39). On the end of the 

 short branches are produced 

 sterigmata, each of which 

 bears a single conidium. Coni- 

 dia are hyaline, thin-walled, 

 spherical when young, but oval 

 when mature (fig. 39). Coni- 

 dia germinate readily by the 

 production of one or two germ 

 tubes. Germinating conidia are 

 found frequently on infected 

 leaves. Oospores have not been 

 found. 

 Control. — The method of infection and spread of the disease 

 is unknown; therefore, no control can be indicated except to 

 suggest sanitation by burning all infected plants and by crop 

 rotation. 



DRY rot: sterile fungus 



Symptoms. — Kernels on the ear are destroyed by a dense 

 felty mass of mycelium. The ear is attacked before maturity 



Sclerospora maydia (Rac.) Butl. 

 a, conidiophore with conidia, 

 arising from stomata of leaf 

 (X 820) ; 6. conidia (X 820) ; 

 e, Kerminating conidia ( X 820 ) . 



