PODBLIGHT OF THE FIMA BEAN CAUSED BY 
DIAPORTHE PHASEOLORUM 
By L. L. Harter, 
Pathologist , Cotton, Truck , Forage Crop Disease Investigations , Bureau of Plant 
Industry , United States Department of Agriculture 
INTRODUCTION 
The Lima bean (Phaseolus lunatus L,), compared with some of the other 
truck crops, is relatively unimportant from a commercial standpoint. It 
is grown in a small way in the garden by nearly every farmer, and on a 
commercial scale in a few sections of the United States, particularly 
along the Atlantic seaboard and along the Pacific coast. Like many 
other crops grown only for home use or on a commercial scale in a limited 
area, its several pests and diseases have either been overlooked or ignored. 
The Lima bean, however, has its share of diseases, some of which have 
been fairly well studied, while little is known about others. To the 
latter class belongs the podblight, a disease of considerable economic 
importance some seasons in commercial fields. It was first discovered 
by Halsted (16) 1 in 1891, in New Jersey. Further than this nothing is 
known as to the time and place of the origin of the disease. 
There is no evidence from the search of the literature that the disease 
occurs outside of the United States, although it is impossible to state 
definitely that it does not, in view of the great number of species of 
Phoma, Phyllosticta, and closely related genera under which the casual 
fungus may have been described. A careful search through the descrip¬ 
tions of species of the genera Phoma, Phyllosticta, and Phomopsis on 
different species of Phaseolus has revealed none located in foreign coun¬ 
tries identical with the organism causing the podblight. It therefore 
appears safe to assume at the present time that the disease is indigenous 
to the United States. 
To judge from published accounts, Halsted (16) was the first to recog¬ 
nize this disease and found it causing much damage to the pods of pole 
Lima beans in New Jersey in the fall of 1891. He attributed it to a 
species of Phyllosticta, pointing out at the same time that large blotches 
were also produced on the leaves. That he studied the disease with some 
care and did not content himself with a few passing observations is 
evident from the fact that he found that the seeds from infected pods, 
when placed under a suitable environment, such as between moist cloths 
or paper, developed the fruiting bodies of the fungus. 
1 Reference is made by number (italic) to 'i' Lterature cited,” p. 502-504. 
Journal of Agricultural Research, 
Washington, D. C. 
kx 
(473) 
Vol. XI, No. 10 
Dec. 3,1917 
Key No. G—128 
