Missouri Botanical 
Garden Bulletin 
Vol. VII St. Louis, Mo., May, 1919 No. 5 
PLANT CANCER 
For several years the appearance of a destructive disease 
upon the marguerites, or Paris daisy, grown under green- 
house conditions has caused considerable concern among the 
growers. The same conditions have been observed at the 
Garden, and it seems desirable to indicate the symptoms and 
causes of this injurious disease and its possible remedies. 
Its occurrence was first noted in Europe about fifty years 
ago, and its cause variously ascribed to frost injury, fungi, 
slime moulds, various sm animals, and mechanical inju- 
ries. The first turn in the right direction was given: by 
Corvo and Cuboni in their contention that the causal organ- 
ism was bacteria. However, since no definite proofs were 
presented, it is thought that theirs was a happy guess based 
upon the resemblance of the tumors to the tubercles of the 
olive which were caused by bacteria. In 1897 Cavara de- 
_ seribed a tuberculosis of the grape, and by careful methods 
of pure culture and successful inoculation of the se seen a 
obtained proved bacteria to be responsible for the isease 
A tumor of the rose was ascribed in 1903 by Scalia to bac- 
terial origin. 
In the United States a number of experiment station work- 
ers (Thaxter, Halsted, Selby, etc.) proved the peach gall to 
be infectious; but it was left to Dr. E. F. Smith, of the Bu- 
reau of Plant Industry, to isolate the causal organism and 
jto successfully carry out cross inoculations, thus proving its 
definite relation to the disease and demonstrating its effects 
upon numerous plants. 
In 1904 a number of white and yellow varieties of mar- 
guerites (Chrysanthemum frutescens) affected with gall-like 
owths on leaves and stems were received by the Bureau of 
Plant Industry. An accompanying statement indicated that 
both young and old plants were attacked, but that the older 
were more seriously affected. The appearance of the galls 
was noted outdoors in the summer and in the greenhouses 
(51) 
