VOLUME VII. 
No. I. 
JOURNAL OF MYCOLOGY. 
SWEET-POTATO BLACK ROT. 
(Ceratocystis fimbriata, Ell. & Hals.) 
By B. D. Halsted and D. G. Fairchild.* 
(Plates I—III.) 
There are several fungous diseases of the sweet potato known under 
the general term of rots,t but none of them have equaled in destruc¬ 
tiveness the one here to be considered, namely, the black rot. It is by 
no means a new trouble, for many persons who have grown sweet pota¬ 
toes for fifty years state that they have known of it from boyhood. 
The common testimony is, however, that it has increased gradually 
from year to year, until now in some parts of the country the disease is 
so bad as to be alarming. 
In order to obtain definite data as to the prevalence of the black rot 
in New Jersey, one of the leading sweet potato growing States, a spe¬ 
cial bulletin of questions was sent to several hundred of the leading 
growers. From the replies it was evident that in nearly all portions of 
the State where sweet potatoes were grown they had been troubled with 
the black rot. Portions of Maryland and Delaware and the large sweet- 
potato region of Virginia have also more or less of the disease; in fact, 
so far as our observation goes, no region is entirely exempt. The exact 
geographical limits of the disease, however, have not been fixed, and 
whether or not it is strictly American remains to be ascertained. 
The chief damage is seen after some months of storage, when the 
decay spreads rapidly from root to root, sometimes destroying as much 
as 25 to 30 per cent of the entire crop. Although no accurate data 
* Both Mr. Fairchild and Dr. Halsted having done considerable independent work 
on sweet-potato diseases, it was thought best to combine their results. With this end 
in view, Mr. Fairchild spent some time in Dr. Halsted’s laboratory in New Bruns¬ 
wick, N. J., where the work done in the Department by Mr. Fairchild and in the 
former place by Dr. Halsted was carefully compared and carried to more complete 
results. This paper represents a portion of the work.—[B. T. G.] 
t Some Fungous Diseases of the Sweet Potato, Bulletin 76, N. J. Experiment Sta¬ 
tion, November 28, 1890, pp. 32, figures 19. 
4289—No. 1—1 
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