July 29, 1918 
A Hitherto-Unreported Disease of Okra 
211 
At the same time that this last pod experiment was carried out, leaves 
were sprayed with spores suspended in water, but no infection resulted. 
Since infected leaves were never found on diseased plants under field con¬ 
ditions, and spraying under artificial conditions yielded negative results, 
it is believed this is a disease of the pods and stems only. 
Apparently several varieties of okra are susceptible to podspot. 
Infection takes place under natural conditions probably only when the 
pods are young, since old or nearly mature pods when wounded or inocu¬ 
lated usually resisted the fungus or showed but a slight indication of 
infection about the wound. 
CULTURAL CHARACTERS 
Ascochyta abelmoschi can readily be isolated in pure culture by the 
poured-plate method after a thorough washing of the infected pods, fol¬ 
lowed by surface disinfection in mercuric chlorid. It grows well on most 
of the agars, stems of Melilotus alba, cooked Irish potato cylinders, 
steamed rice and steamed com meal. The maximum mycelial growth is 
made on agars and the minimum on Melilotus stems. On the other hand, 
it fruits sparsely on agars and abundantly on stems of M. alba. Growth 
is noticeable on most any of the media in common use in 24 to 48 hours 
at laboratory room temperature. On steamed rice and on steamed Irish 
potatoes an ocherous color appears in 48 hours and increases in intensity 
for several days. This color later gives way to a dirty ocherous color 
brought about largely by the development of the pycnidia. 
Pycnidia develop not at all or sparingly on most of the agars. On 
stems of Melilotus alba they begin to appear in three days and to exhude 
spores in seven days. Pycnidia develop on rice and Irish potato cylinders 
in about three to four days and exhude spores in about eight days. 
Stems of M. alba , cooked rice, and Irish potato cylinders are good media 
for the growth of the fungus. 
SUMMARY 
(1) Ascochyta abelmoschi is parasitic upon the stems and pods of several 
varieties of okra. 
(2) The disease caused considerable loss where it occurred in Maryland 
in 1916. 
(3) The disease also occurs in New York State. 
(4) The origin of this disease in Maryland is doubtful. Either it may 
have been imported with the seed or it may have originated from domestic 
sources. 
(5) The fungus grows well on most any of the culture media in common 
use, but fruits the best on stems of Melilotus alba and cooked rice. 
