May 1. 1920 Philippine Downy Mildew of Maize 117 



sterigmata, however, are comparable, and it is clear that those of the 

 British Indian fungus are markedly larger (15 to 20 m long) than those 

 of the Philippine species. 



Moreover, the field characteristics are noticeably different. Although 

 Butler reported the first attack of the disease at Pusa in 191 2 and empha- 

 sized the probability of its spreading to other fields of the region, his 

 latest report (5) indicates that it has continued to be only slightly and 

 restrictedly destructive, an effect markedly in contrast to the rapid 

 spread and serious damage of the Philippine fungus. Also, Butler's 

 description emphasizes the stunting of the growth and resultant bunchy 

 appearance of the plant as a characteristic feature of the disease in India, 

 while in the Philippines this is but one and certainly not the most striking 

 effect of the disease. 



While the matter is necessarily unsettled because of lack of adequate 

 description of the British Indian form, certain points would seem to 

 indicate that the maize-mildew of India is a different physiological 

 variety and probably a different species from that of the Philippines. 

 These points are the differences in the causal fungi and the symptoms, 

 and especially the lack of virulence shown by the Indian disease and its 

 failure to spread through Bengal where "maize is a crop of considerable 

 importance" and where the conditions of climate and culture are little 

 if at all different from those of some infested regions of the Philippines. 



In any case, however, it should be noted that the name Sclerospora 

 maydis (Rac.) But. is not strictly a tenable one, for it was applied to the 

 British Indian maize-mildew by Butler (5, p. 15) on the assumption that 

 it was identical with the Javan. Butler {4, p. 2j 5-276) concluded from 

 his comparison with the diagrammatic drawings and incomplete descrip- 

 tions of Raciborski {16) that the downy mildew of maize in British 

 India — 



was found to be identical with the one which causes great damage to this crop in 

 Java, 



and that — 



its cause is a fungus named Peronospora maydis by Raciborski. 



The more recent and extensive work of Palm {15), however, has shown 

 clearly that the Javan fungus, although indeed a Sclerospora, is a dis- 

 tinct species, one which Palm names Sclerospora javanica. This leaves 

 Sclerospora maydis (Rac.) But. as the name of the British Indian maize- 

 mildew. 



Therefore, because the points of difference already considered seem to 

 indicate that the downy mildew of maize in the Philippines is not identical 

 with the one in British India, and because the name Sclerospora maydis 

 (Rac.) But., given to the latter, is technically untenable, it seems nec- 

 essary to distinguish the Philippine downy mildew of maize. Hence it is 



