STEM AND ROOTROT OF PEAS IN THE UNITED 
STATES CAUSED BY SPECIES OF FUSARIUM 1 
By Fred Reuse Jones 
Pathologist, Office of Cotton, Truck, and Forage Crop Disease Investigations, Bureau of 
Plant Industry, United States Department of Agriculture 
INTRODUCTION 
It is a well known fact learned through the costly experience of pea 
growers in the older portions of the United States that in many localities 
when peas are grown repeatedly on the same ground the time comes 
sooner or later when they thrive less vigorously, and finally fail com¬ 
pletely. After such a failure, the ground must be devoted to other 
crops for several years before peas can be grown again with any degree 
of success, and often the ground appears to be permanently ruined for 
pea growing. Experience similar to this has long been known in Europe 
and Asia wherever peas are grown; but it appears to have been felt 
more keenly in America where the development of the canning industry 
has stimulated the intensive culture of peas in small areas close to can¬ 
ning establishments. 
This failure of peas is always found upon examination of the plants 
to be due to a decay of the base of the stem and of the roots of the plants. 
The cause of this decay has been sought by a number of investigators 
in Europe and America, and a considerable list of parasitic fungi have 
been accused on the basis of evidence of varying value. These several 
investigations, conducted in limited areas and arriving at diverse results, 
have not furnished pathologists criteria whereby they may either deter¬ 
mine which of the several diseases are present in any new locality, 
or initiate control measures on the basis of a knowledge of the life his¬ 
tory of the parasite to be combated. Most important of all, no evi¬ 
dence has been provided which can indicate whether these diseases can 
be kept out of new pea-growing regions that are being developed. This 
situation led in the summer of 1918 to the assignment of the writer to 
the task of determining the parasites causing decay of roots and basal 
portions of the stems of pea plants in the pea-growing regions of the 
United States where trouble has been experienced., As a result of this 
investigation, which is now approaching completion, it has been found 
that four parasitic fungi are the chief factors in producing decay of the 
underground portions of the pea plant in all the localities examined. 
These fungi are a species of Fusarium previously found but not named 
by G. R. Bisby in Minnesota, an undescribed species of Aphanomyces, 
Pythium debaryanum , and Corticium vagum . Although these four fungi 
usually occur together wherever rootrot of peas is serious, and although 
they cause diseases that can not always be distinguished from each other 
with certainty by visible symptoms, yet these four fungi are factors of 
such distinct character in their contribution to crop failures that they 
will be discussed separately. This paper deals with the disease caused 
1 Accepted for publication October 3, 1923. 
(459) 
Journal of Agricultural Research, 
Washington, D. C. 
aib 
Vol. XXVI, No. xo 
Dec. 8,1923 
Key No. G-343 
