July 29, 1918 
A Hitherto-Unreported Disease of Okra 
209 
Ascochyta abelmoschi, n. sp. 
Spots somewhat circular, often with a brown to black margin, more 
or less distinctly zonate; pycnidia gregarious, often crowded together, 
brown to black, lenticular, pyriform to globose, rather thick walled, at 
first buried, becoming finally erumpent, 65 to 225 ju in diameter, ostiolum 
small, mostly central; 
pycnospores, cylindrical to 
oval, straight or curved, 
4.0 to 14.0 by 2.1 to 
4.5 /x, hyalin, 1-celled for 
a long time, finally septat- 
ing transversely at the cen¬ 
ter, then or not at all 
slightly constricted, 
rounded at the ends, when 
guttulate 2 to 4. 
Type specimens are de¬ 
posited in the herbarium 
of the Pathological Collec¬ 
tions of the Bureau of 
Plant Industry, United 
States Department of Agri¬ 
culture. 
While the pycnidia are 
relatively small when on 
the host, they are very 
much larger and more variable in shape when grown in artificial 
cultures. 
The pycnidium is inclosed in an outer darkwall about one or two cells 
in thickness (fig. 1). Within this is a somewhat thicker hyalin layer 
from which the rather stout blunt conid- 
iophores arise (fig. 2). The ostiolum ar¬ 
ranged centrally on the host is variously 
placed when the fungus is grown in arti¬ 
ficial cultures. It is small, slightly drawn 
out, and the pycnidial walls surrounding it 
are slightly thicker and darker than at 
other parts of the pycnidium. 
The spores (fig. 3),produced in great num¬ 
bers, are hyalin and for a long time 1-celled. In old cultures and in the 
later stages of the development on the host some of the spores lay down 
a septum near the middle. Different specimens, as well as different 
cultures, vary as to the percentage of 2-celled spores, but no case has 
been found where more than 50 per cent of the spores have septated. 
Fig. i .—Ascochyta abelmoschi: A section through a pycnidium 
on the host showing the outer and inner wails, the sporo- 
phores and pycnospores. X 500. 
Fig. 2 .—Ascochyta abelmoschi: A por¬ 
tion of the pycnidium shown in figure 
1. X 1.000. 
