jan. 27,1923 Production of Conidia in Philippine Sclerosporas 277 
also effected, though to a much less degree, by agents of minor importance, 
such as surface water, insects, and moist soil laden with conidia. 
The genus Sclerospora may be disseminated in three stages of its devel¬ 
opment—as mycelium, as oospores, and as conidia. (1) Mycelium, in 
the case of maize itself, plays no part in disseminating the Philippine 
downy mildews. However, as mycelium in cuttings of other hosts, such 
as sugar cane and related grasses, these diseases are distributed in the 
Philippine Islands and thus could be brought to the United States. (2) 
The oospore stage is not found on maize in the Philippines. Whether the 
oogonial Sclerosporas occurring on sugar cane and two wild grasses in the 
islands are related to maize is not known. However, this stage must be 
responsible for at least some of the local and distant spread of these fungi 
and may possibly be involved also in the dissemination of the conidial 
phases on maize. (3) Not only during any one season but from year to 
year conidia are the most important means cf accomplishing both locally 
and extensively the destructive spread of the downy mildews on maize 
throughout the Philippine Islands. Spread to the United States could 
not be accomplished by conidia unless these developed on plants imported 
alive. If the disease were introduced in any fashion, however, the coni¬ 
dia would be of the greatest importance in rapid dissemination. 
LITERATURE CITED 
(1) Baker, C. F. 
1916. additional notes on Philippine plant diseases. In Philippine Agr. 
and Forester, v. 5, no. 3, p. 73-78. 
(2) Buller, A. H. Reginald. 
1909. researches on fungi . . . 287 p., 83 fig., 5 pi. London, New York, etc. 
(3) Butler, E. J. 
1913. THE DOWNY MILDEW OF MAIZE (SCLEROSPORA MAYDIS (RAC.) BUTL.). In 
Mem. Dept. Agr. India, Bot. Ser., v. 5, no. 5, p. 275-280, pi. 8-9. 
(4) — 
1917. THE DISSEMINATION OF PARASITIC FUNGI AND INTERNATIONAL LEGISLA¬ 
TION. In Mem. Dept. Agr. India, Bot. Ser., v. 9, no. 1, p. 1-73. 
(5) Coons, George Herbert. 
1912. SOME INVESTIGATIONS OF THE CEDAR RUST FUNGUS, GYMNOSPORANGIUM 
junipEri-Virginianae. In Nebr. Agr. Exp. Sta., 25th Ann. Rpt., p. 
215-245, pi. 1-3. Bibliography, p. 239-242. 
(6) Dickhoff, W. C. 
1912. BIJDRAGE TOT DE KENNIS VAN DEN ANATOMISCHEN BOUW VAN DEN 
Epidermis van het rietblad. In Arch. Suikerindus. Nederland.- 
Indie, Jaarg. 20, Deel 1, Afl. 4, p. 67-75, pi. 1-5. 
(7) Duggar, Benjamin M. 
1911. PLANT PHYSIOLOGY WITH SPECIAL REFERENCE TO PLANT PRODUCTION, 
xv, 516 p., 144 fig., i pi. New York. Bibliographies at ends of chap¬ 
ters. 
(8) Eckerson, Sophia H. 
1908. THE NUMBER AND SIZE OF THE STOMATA. In Bot. Gaz., V. 46, no. 3, p. 
221-224. 
(9) Faulwetter, R. C. 
1917. dissemination of the angular lEafspot of cotton. In Jour. Agr. 
Research, v. 8, no. 12, p. 457-475, 2 fig. Literature cited, p. 473-475. 
(10) — 
1917. WIND-BLOWN RAIN, A FACTOR IN DISEASE DISSEMINATION. In Jour. Agr. 
Research, v. 10, no. 12, p. 639-648, 1 fig. 
(11) Fischer, Alfred. 
1892. phycomycetes. 5o5p.,illus. Leipzig. (Rabenhorst, Ludwig. Krypto- 
gamen-Flora von Deutschland, oesterreich und der Schweiz. Aufl. 2. 
Bd. 1, Abt. 4.). 
