THE DOWNY MILDEW OF MAIZE 



(Sclerospora Maydis (Rac.) Butl.) 



BY 



E. J. BUTLER, m.b., f.l.s., 

 Imperial Mycologist. 



A disease of maize, not previously known in India, appeared 

 on the Pusa Farm last year (1912). It was found to be identical 

 with one which causes great damage to this crop in Java, where it 

 is termed by the natives " lijer " or "sleepy" disease. Raci- 

 borski 1 , who first described it in 1897, prophesied its extension 

 from Java to other maize-growing countries in the future ; it is 

 certainly of recent appearance at Pusa and it is probable that it 

 has reached India from Java since Raciborski wrote. Up to the 

 present it has not been recorded anywhere else, and we have no 

 information as to its distribution in India or the rest of South- 

 eastern Asia. 



The disease becomes apparent before the plants have attained 

 their full growth. The lower leaves are usually normal, but the 

 upper part of the plant is chlorotic, owing to the disappearance of 

 the leaf chlorophyll in long streaks (PL VIII). The growth of the 

 plant is checked and the internodes frequently shortened so as to 

 give a bunchy appearance to the head (PI. IX, Fig. 6). The affected 

 plants are easily recognised at a distance, by their pale colour 

 and stunted bunchy growth. Such plants do not usually produce 

 any grain, though sometimes small cobs are borne. The tassel or 

 male inflorescence is more commonly developed and may be quite 

 normal. The whole plant withers and dies, as a rule, some weeks 



1 Raciborski, M. Lijcr, eine gcfiihrlichc Maiskrankheit, Bcr. d. L>cutsch Bot. Gesellsch. 

 XV, 1897, p. 475. 



