2 30 
Journal of Agricultural Research 
Vol. VIII, No. 6 
The following is a brief description of the fungus under discussion: 
Helicosporiiun nymphaearum, n. sp. 
Upon leaves of pond lilies (Nymphaea spp.), causing initial brown to reddish flecks, 
developing into irregular olivaceous-black water-soaked spots, which individually or 
by coalescence may in some cases involve the greater part of the leaf blade. 
Mycelium light brown, intercellular, often hyalin in culture, septate, branched, 
growing readily on ordinary culture media. 
Sporophores long and slender and bearing several conidia near the summit (PI. 
69, D). Conidia brown, many septate, constricted at the septa, usually somewhat 
larger toward the basal end, slightly tapering toward the curved or usually helicoid 
apical end (PI. 69, C, E ); outer walls thick and with echinulate sculpturings (PI. 
69, D, F, G) ; cross walls with roundish thin spot or perforation in the center (PI. 69, B) ; 
highly variable in size (60 to 190 by 5 to i8ju); not readily produced on diseased leaves 
in damp chamber but develop in large numbers on several of the ordinary culture 
media. Sclerotia roundish, subcarbonaceous, develop sparingly on leaves and in 
culture, 150 to 900^ diameter. 
Habitat: Leaves of Nymphaea spp. TyP e specimens from aquatic gardens at 
Kenilworth, D. C. Specimens also collected from open ponds at Riverton and Arling¬ 
ton, N. J., at the Brooklyn Botanical Gardens, Brooklyn, N. Y., and at the New York 
Botanical Garden, New York City. 
Helicosporium nymphaearum, sp. n.—Maculis in foliis primo minutis fuscis vel subrufis, deinde sub- 
nigris, aquosis et irregularibus, interdum conjunctis postremo; mycelio albidofusco, intercellular^ septato, 
ramose; saepe in culturis hyalino, sporophoris longis, tenuibus, multas conidias prope apicem habientibus; 
conidiis fuscis, multiseptatis, in septis constrictis, in basi et apice plerumque attenuatis; apicibus conidi- 
arum curvatis ve! plerumque helicoideis; muris conidiarum densis, echinatis; conidiis 60-190/i X 5-18ju; 
Sderotiis subsphaericis, subcarbonaceis 150-900/i. 
Hab. in foliis vivis Nymphaeae speciorum, Washington, D. C,, Arlington et Riverton, N. J., New 
York, N. Y. America Borealis. 
CONTROL OF THE DISEASE 
The control of diseases of aquatic plants has been little studied. In 
fact, the only account of actual experiments along this line which has 
come to the attention of the writer consists in a brief account of tests 
for the control of a leaf spot of pond lilies 1 apparently due to a species 
of Cercospora. No cultural or inoculation experiments with the parasite 
are mentioned, but a description is given of a single series of experiments 
with Bordeaux mixture, oxid of copper mixed with sulphur, sulphur 
alone, and ammoniacal copper carbonate applied by adding to the water 
m tubs in which the plants were growing. The Bordeaux mixture is 
described as giving satisfactory results but as being objectionable on 
account of its appearance on the foliage. Ammoniacal copper carbonate 
was preferred to the Bordeaux mixture, but it had to be used in weak 
solution to prevent injury. The sulphur treatments were unsatisfactory. 
A secondary advantage from use of the fungicides consisted in the destruc¬ 
tion of the green algae. Spraying with Bordeaux mixture is also Recom¬ 
mended by Bisset 2 as an efficient control against the leaf spot of pond 
lilies caused by Cercospora sp., but no direct experiment is mentioned. 
1 Halsted, B. D. Experiments with water-lily blight. In N. J. Agr. Exp. Sta., 17th Ann. Rpt. [1895J/1896, 
p. 405-407. fig. 52. 1897. 
2 Bisset, Peter. The Book of Water Gardening . . . p. 188-189. New York, 1907. 
