TWO DISEASES OF UDO (ARALIA CORDATA THUNB.) 1 
By J. I/. Weimer 
Pathologist, Office of Cotton, Truck, and Forage Crop Disease Investigations, Bureau of 
Plant Industry, United States Department of Agriculture 
In the summer of 1920 the writer’s attention was called to two diseases 
of udo which were apparently of different origin. A specimen of one, 
a rootrot, was sent to the Office of Cotton, Truck and Forage Crop Disease 
Investigations, United States Department of Agriculture, by Dr. David 
Fairchild. The other disease was killing the udo plants in the garden of 
Dr. W. A. Orton at Takoma Park, D. C. The writer undertook to 
determine the cause of these diseases, and the purpose of this paper is to 
record his findings. 
HOST 
The udo is a species of Aralia, namely, Aralia cordata Thunb., introduced 
into the United States in 1903 by Lathrop and Fairchild from Japan, 
where it is grown extensively for food. It is a hardy perennial plant 
which produces strong young shoots each spring. These are blanched 
and used as a vegetable like asparagus. The plants are usually grown 
from seed, although they may be propagated by cuttings. They sometimes 
grow to be from 4 to 6 feet high the first season. After the first frost 
the tops die down and the plant remains dormant during the winter, 
coming up again the following spring much the same as do asparagus and 
rhubarb. The general character of this plant is apparent from the illustra¬ 
tions. For further details regarding its history, habits of growth, and 
methods of cultivation, the reader is referred to a paper by Fairchild (5). 2 
ROOTROT 
The first specimen of this disease seen by the writer came from Dr. 
Fairchild’s farm near Chevy Chase, Md. Other specimens were received 
later from the same source, as well as from a planting at Bell, Md. What 
appears to be the same disease was reported by Fairchild (5) to have been 
present in his first udo planting, regarding which he states, “The writer 
discovered a soft rot of the roots which killed a number of apparently 
vigorous plants on the farm of the Department of Agriculture at Arling¬ 
ton, Va., the cause of which proved to be a sclerotium-producing fungus, 
the mature form of which has not yet been observed.” No experimental 
data are given to show that the sclerotium-producing fungus mentioned 
was the cause of the disease, and Dr. Fairchild requested further informa¬ 
tion regarding the cause of this trouble. 
Diseases resulting from sclerotium-producing fungi seem to have 
attained unusual prominence during the past few years. A disease of 
lettuce known as “drop” caused by Sclerotinia libertiana Fcl. has long 
been known and studied. More recently a disease of sunflower ( Helian - 
thus annuus L.) has been described by Bisby (z), who did not determine 
the causal organism, but states that it is very similar to Sclerotinia liber - 
1 Accepted for publication Aug. n, 1923. 
2 Reference is made by number (italic) to “literature cited," p. 278. 
(271) 
Journal of Agricultural Research, 
Washington, D. C. 
able 
Vol. XXVI, No. 6 
Nov 10, 1923 
Key No. G-335 
