May 1. 1920 Philippine Downy Mildew of Maize 121 



(7) Maize plants usually are infected as very young seedlings, and less 

 often as they mature. In any case, however, when the symptoms appear, 

 the mycelium of the fungus already has invaded the host tissue exten- 

 sively. The mycelium may be found in practically every part of the maize 

 plant with the exception of the root, but is most abundant among the 

 bundle sheath cells of the leaf. 



(8) The conidiophores are produced in vast numbers but only at 

 night when a thin layer of dew or rain is on the leaf surface. They vary 

 greatly in size and development according to the depth and persistence 

 of this layer. These variations are described and figured. 



(9) Since the conidia also show wide variation in size and shape, an 

 attempt is made to give a quantitative idea of this by tables and graphs 

 of the measurements of 400 specimens. When fresh, the conidia ger- 

 minate readily in water and various culture media at temperatures rang- 

 ing from 6.5° to 25° C, and invariably by hyphae. Once they have 

 become dried the conidia no longer germinate; hence their distribution 

 and the infection of new plants occurs almost always before dawn. 



(10) In spite of extensive search, no oospores or other resting bodies 

 have yet been found to be produced by this Sclerospora. It apparently 

 maintains itself by transmission from plant to plant; The writer has 

 found the oospore stage of a new Sclerospora on Saccharum spontaneum 

 L., a common wild grass of the Philippines. Whether this is in any way 

 connected with the conidial stage on maize remains to be determined. 



LITERATURE CITED 

 (i) Baker, C. F. 



1916. ADDITIONAL NOTES ON PHiLrppiNE PLANT DISEASES. In Philippine Agr. 

 and Forester, v. 5, no. 3, p. 73-78. 



(2) Berlese, E. J. 



1898-1904. SAGGIO DI UNA MONOGRAFIA DELLE PERONOSPORACEE (1898-1903). 



In Riv. Patol. Veg., s. 2, v. 6, p. 79-110, pi. 7-10; v. 7, p. 19-37, 

 1898; V. 9, p. 1-126, illus., 1901; V. 10, p. 185-298, illus., 1904. 

 Reprinted. 



(3) Butler, E. J. 



1907. SOME DISEASES OF CEREALS CAUSED BY SCLEROSPORA GRAMINICOLA. In 



Mem. Dept. Agr. India Bot. Ser., v. 2, no. i, 24 p., 5 pi. 



(4) 



1913. THE DOWNY MILDEW OF MAIZE (sCLEROSPORA MAYDIS (rAC.) BUTL.). Ill 



Mem. Dept. Agr. India Bot. Ser., v. 5, no. 5, p. 275-280, pi. 8-9 (i col.). 



(5) 



1918. FUNGI AND DISEASES IN PLANTS . . . 547 p., illus., pi. Calcutta. Bib- 

 liography, p. 518-531. 



(6) Gaumann, Ernst. 



1918. UBER DIS SPEZIALISATION OER PERONOSPORA AUF EINIGEN SCROPHULARIA- 



CEEN. /« Ann. Mycol., v. 16, no. K- P- 189-199, 6 fig. Zitierte Liter- 

 atur, p. 199. 



(7) Griffiths, D. 



190/. CONCERNING SOME WEST AMERICAN FUNGI, /n Bul. Torrey Bot. Club, v. 

 34, no. 4, p. 207-211. (Continued article.) 



