62 Report OF THE BACTERIOLOGIST OF THE 
VITALITY OF THE CABBAGE BLACK ROT GERM ON 
CABBAGE SEED. 
H. A. Harpine, F. C. Stewart AnD M. J. Prucwa. 
SUMMARY. 
Black rot of cabbage is a destructive bacterial disease caused 
by Pseudomonas campestris (Pam.) Smith. No satisfactory 
method of controlling the disease in the field: has yet been found. 
Concerning the ability of the disease germs to survive the winter 
on the seed, there has been a difference of opinion. The present 
bulletin gives an account of some investigations bearing on this 
point. 
The conclusion is that much of the cabbage seed on the market 
is contaminated with germs of the black rot disease and that some 
of these germs may survive the winter and become a source or 
infection to the young cabbage plants. 
As a precautionary measure, it is advised that all cabbage 
seed be disinfected before sowing, by soaking for fifteen minutes 
in a 1-1000 corrosive sublimate solution or in formalin, one pound 
to thirty gallons. It is not expected that this treatment will 
prevent either leaf or root infection in infected soils; but it may 
be safely relied upon to prevent all danger from infected seed. 
It will not injure the germination. 
INTRODUCTION. 
Black rot in cabbage is primarily a trouble of the fibro-vascular 
bundles. During the progress of the disease these bundles become 
dark brown or black. On cutting across the petiole of a dis- 
eased leaf the affected bundles are seen as dark points. When so 
many of the bundles are affected as to cut off the supply of 
water to a leaf the blade dries up and resembles a piece of brown 
1A preliminary note on this investigation was published in Science, N. 8S. 20: 
55. July 8, 1904. A reprint of Bulletin No. 251. 
