JOURNAL OF MEWL RESEARCH 
Vol. XXV Washington, D. C., July 21, 1923 No. 3 
SOME RELATIONS OF THE CROWNGALL ORGANISM 
TO ITS HOST TISSUE 1 
By A. J. Riker 2 
Instructor , Department of Plant Pathology , University of Wisconsin 
INTRODUCTION 
For a number of years crowngall has been reported to be a limiting 
factor in Wisconsin in the cultivation of certain cane fruits. A recent 
survey by Jones (2 ) 3 revealed its presence in practically all the com¬ 
mercial cane fruit plantings in the State, and confirmed the earlier 
judgments as to its economic importance. Consequently, the writer 
undertook an investigation of this disease in the summer of 1920, with 
the aim of directing his efforts primarily along lines which promised to 
lay the foundation for more effective control measures. 
In the early stages of this work it was decided to conduct preliminary 
studies upon the tomato, since it can be grown easily in the greenhouse 
in winter and is very susceptible to crowngall. While tomato stems 
were being inoculated by punctures, it was noticed that a water-soaked 
area promptly appeared about the point of entry of the needle. 
It seemed evident that this darkened area, which tended to be parallel 
to the long axis of the plant, was caused by the occupancy of the inter¬ 
cellular spaces by liquid (PI. 1, F, G). Sometimes, as seen from the 
surface, this water-soaked area attained a length of more than a centi¬ 
meter, being especially conspicuous if the plant was quite turgid. No 
particular significance was attached to this observation until it was 
noted that the subsequently developed tumor appeared to conform 
closely in outline with this water-soaked tissue. Inoculations were then 
made in which the outlines of the water-soaked regions were marked 
with India ink. When the galls developed, they were found to coincide 
almost exactly in outline with the marked areas (PI. 1, G, H). These 
results did not seem to accord with the generally accepted idea that 
the gall developed as a result of the stimulus from organisms which had 
gained entrance to the interior of the cells ( p . 5, p. 2; 9, p. 287; 10, 
p. 419 ). The observed facts seemed rather to indicate the possibility that 
the organism began its activities in the liquid which occupied* the inter¬ 
cellular spaces around the puncture. 
1 Accepted for publication May 2, 1923* 
* The writer takes pleasure in expressing his indebtedness to Dr. L. R. Jones and Dr. G. W. Keitt, of the 
University of Wisconsin, and also to other members of the faculty, especially Dr. S. Eckerson and Dr. E. J. 
Kraus for many valuable suggestions in the prosecution of these studies. 
8 Reference is made by number (italic) to “Literature cited,” p. 132. 
Journal of Agricultural Research, 
Washington, D. C. 
afn 
Vol. XXV, No. 3' 
July 21, 1923 
Key No. Wis.-aa 
(119) 
48109—23-1 
