July 15, 1914 
Fusarium on Sweet Potato 
271 
12a. Hypomyces cancri (Rutgers), n. comb. 1 (Pis. XIII, /, and XV, B-C). 
Nectria ccmcri Rutg., 1913, in Ann. Jard. Bot. Buitenzorg, v. 27 (s. 2, V. 12), pt. 1, p. 62. 
Diagnosis.—In general appearance this species resembles Hypomyces ipomoeae , but 
differs in having a lower average septation of the conidia, larger perithecia, and larger 
ascospores. Contrary to H. ipomoeae , the conidial stage, especially sporodochia and 
pionnotes, is more prevalent than the ascigerous stage. Perithecia average 350-450 
by 275 to 375/1; ascospores average 10 to 15 by 5 to 6.75/1 in size; conidia largely 3-septate 
average 30 to 45 hy 3-75 to 5J“ (3 to 5 septate conidia average 30 to 55 by 3.75 to 5.5/1 
in size). 
Habitat.—On cankered bark of Theobroma cacao in Java (Rutgers), on dead tap¬ 
roots of Cannabis saliva , Potomac Flats, Washington, D. C., North America (Wollenw.). 
This diagnosis is based on pure cultures of the strain isolated from Cannabis. 
Hypomyces ipomoeae , well known as Nectria ipomoeae Halsted (1892), 
has both true chlamydospores (PI. XIII, fig. D) and conidia of the shape 
described for similar Hypomyces, such as H . solani Reinke and Berthold 
(1879). Such chlamydospores are lacking in pure cultures of Nectria, 
as proved by the writer for the sections Willkommiotes and Tubercu- 
lariastrum (Wollenweber, 1913b, p. 203-204, 226-229). A transfer of 
N. ipomoeae to the genus Hypomyces is therefore advocated (Wollen¬ 
weber, 1913c, p. 34). Since further taxonomic discussion on this fungus 
will be aided by more complete descriptions, additional notes and illus¬ 
trations (Pis. XIII and XV) have been given here. 
This saprophyte, now known to be cosmopolitan and ubiquitous, has 
crossed the path of various pathologists who always thought it was a 
new species when they isolated it from other hosts than eggplant and 
sweet potato. So long as the opinion of its parasitic nature prevailed, 
an adaptation to particular hosts could be supposed, but its saprophytic 
nature established by Harter and Field for sweet potatoes and eggplants 
and by the writer for eggplant leaves no doubt of its indifference regard¬ 
ing the host. 
In pure culture the easy and rapid development of perithecia on almost 
any steamed vegetable recalls the similar omnivorous conduct of other 
saprophytes, such as Melanospora and Chaetomium, while Gibberella 
Saubinetii and Nectria discophora favor some media more than others for 
the production of the perfect form, and Nectria galligena and Caloneciria 
graminicola require a careful selection of media for the completion of their 
life cycle in pure culture. 
Hypomyces ipomoeae has been studied in a number of strains from 
Ipomoea, sent from Ohio, Delaware, and New Jersey, and isolated by L. 
L. Harter and Ethel C. Field, Bureau of Plant Industry; J. J. Taubenhaus, 
Delaware Experiment Station; and Dr. Donald Reddick, Cornell Experi¬ 
ment Station. No essential differences could be detected within two 
yeai^, and it should be noted that Reddick’s strain has been carried 
through cultures since 1907 without showing any degeneration or any 
1 This fungus from hemp, although not yet found on sweet potato, has been discussed in connection 
with Hypomyces ipomoeae , and it was thought advisable to give a short description. 
