670 Journal of Agricultural Research vol. xx, no. 9 



hosts for downy mildew. After long search a clump of bugang grass 

 (Saccharum spontaneum) heavily infected by a conidial Sclerospora was 

 discovered by Mrs. Weston. Continued hunting brought the fungus to 

 light on the same host in two other places, all three cases being encoun- 

 tered in the rugged interior uplands of Cebu (PI. 76), which lie between 

 Carcar and Barili. In the island of Leyte, also, this Sclerospora was 

 again found on bugang grass on a hillside about three miles from Baybay. 

 No other cases of downy mildew either on this or on other hosts were seen. 

 Later, in a field of native sugar cane near Guadelupe cemetery outside 

 the town of Cebu, a single clump of cane was found infected with the 

 conidial stage of a Sclerospora. 



The infected plants of Saccharum spontaneum and sugar cane were 

 transplanted to Los Banos, Luzon, for further study (PI. jj, B). There 

 a comparison of living material taken from these plants during the opti- 

 mum time of nocturnal conidiophore production showed that this downy 

 mildew from the southern islands was different from that previously 

 studied in Luzon. This discovery necessitated a revision of all available 

 material in order to determine whether or not other forms had been pre- 

 viously overlooked under the assumption that the collections were all 

 of the same form so commonly found in Luzon. Accordingly, living 

 material from maize, teosinte, and sorghum from the college plots and 

 from native fields in Batangas and Laguna provinces was compared with 

 the living material from the plants of Saccharum spontaneum and sugar 

 cane brought from Cebu. Dried, preserved, and mounted specimens 

 from maize collected in various parts of Luzon were compared with similar 

 specimens from maize obtained in various localities in Cebu, Bohol, and 

 Leyte. This survey showed clearly that all the material so far encoun- 

 tered fell into one or the other of two distinct species — one, the form 

 with shorter, broader conidia found on maize, etc., in Luzon and pre- 

 viously described as Sclerospora philippinensis, and the other, which will 

 be called Sclerospora spontanea, characterized by longer, narrower conidia, 

 and found on maize, bugang grass, and sugar cane in the Visayas. Once 

 this point had been established, a comprehensive study was made of the 

 two species to determine the resemblances and differences between them 

 in morphological and physiological characteristics. 



COMPARATIVE STUDY OF SCLEROSPORA PHILIPPINENSIS AND 

 SCLEROSPORA SPONTANEA 



FIELD CHARACTERISTICS 



On maize, as observed in the field in the more southern islands and in 

 Luzon, the two species are apparently identical in their destructiveness 

 to the crop as a whole and also in their effect on the individual plants. 

 It is possible that quantitative studies of essentially similar fields infected 

 by the separate species would show some slight differences, but in general 

 appearance there is no distinction whatever between the two. 



