Dec. 3, 1917 
Podblight of Lima Bean 
501 
SUMMARY 
(1) The podblight of Lima beans is probably indigenous to the United 
States. 
(2) It was first recognized by Halsted in New Jersey in 1891, and has 
since been found in the States of Virginia, Maryland, Connecticut, and 
North Carolina. 
(3) The disease forms circular brown spots on the leaves, and large 
unsightly spots on the nearly mature pods and on the stems. Numerous 
pycnidia are produced in the diseased areas. 
(4) The loss, which in some fields is very large, is confined mostly to 
the pods. 
(5) The Lima bean podblight fungus has been known as Phoma 
subcircinata E. and E. almost since its first discovery, although in a few 
cases it has been referred to as a species of Phyllosticta. 
(6) The writer isolated single ascospores of a Diaporthe found on 
specimens wintered out and made inoculations with pure cultures of 
such strains which produced a disease identical with that produced by 
inoculations with pure cultures of a pycnospore strain. In 1892 Diaporthe 
phaseolorum was completely described, which agrees with the ascogenous 
fungus the writer has been studying. The fungus causing the disease 
is therefore referred to as Diaporthe phaseolorum (C. and E.) Sacc. 
(7) The hyphae course through and among the parenchymous cells 
of the pod, forming pycnidia just under the epidermis at points where 
the bast cells are more or less separated. 
(8) Stylospores are abundantly found on field material and readily 
produced in culture on some media. The pycnospore stage belongs to 
the form genus Phomopsis and not to Phoma. 
(9) The disease is readily produced by artificial inoculation with spores 
from both the pycnidial and ascogenous strains. 
(10) Wounding of the pod is not necessary for infection, as the germ 
tubes may enter through the stomata. 
(11) The fungus is carried through from one season to the next, either 
by periodic production of pycnospores and the persistence of hyphae or 
by the production of an ascospore stage. 
(12) The disease may be carried on the seed and spread by such 
agencies as wind, by the process of picking, and possibly by means of 
insects. 
(13) The fungus fruits well on stems of Melilotus alba , on rice, com 
meal, and other starch media, and but poorly or not at all on the agars 
tried with the exception of corn-meal agar. 
(14) Cultures in the dark fruited more slowly than those in the light 
and had increased vegetative growth. 
(15) No growth takes place at a temperature below 6.1 0 nor higher 
than 35.4 0 C. during a period of 27 days. 
