BACTERIA 519 



entrance of fungi, etc. Symptoms of the disease are the 

 scanty, pale, small, more or less curled leaves, on a given 

 branch or over the whole tree, depending where the canker is 

 located. It is most fatal when the collar or the angles formed 

 by the larger branches are attacked. Infection takes place, 

 often through the unconscious agency of insects, at points of 

 the bark that have been bruised or wounded in any way, and 

 also through the blighting of adventitious shoots on the trunk 

 or limbs. 



Whetzel, H. H., Cornell Univ. Expt. Sta., Bull. 236 

 (1906). 



Mulberry bacteriosis. The arrest of the growth of young 

 mulberry trees has been noted by Boyer and Lambert in 

 France, who traced the injury to a bacterium they have named 

 Bacterium mori. The injury consists in the arrest of develop- 

 ment of the branches, which is first indicated by the presence 

 of blackish-brown patches on the lower surface of the leaves 

 and young branches. On the branches the spots vary in form, 

 generally elongated and depressed, which eventually become 

 open wounds extending to the pith. 



Boyer and Lambert, Comp. Rend., 128, p. 342 (1893). 



Iris rot. This disease is very prevalent in this country, also 

 on the Continent, and attacks many different kinds of iris. 

 I have repeatedly seen whole beds completely destroyed by 

 it. A single plant may first show the disease, which is indi- 

 cated by the wilting of the leaves, which soon become yellow 

 and die. On removing such a diseased plant, it is found that 

 the portion immediately underground is quite soft and rotten. 

 This condition of things often extends to the rhizome, and 

 when this is the case all offshoots from the rhizome are also 

 infected. 



Dr. C. J. J. van Hall has proved by a series of experiments 

 that the disease is due to bacteria, the most potent factor being 

 Bacillus omnivorus, v. Hall ; Pseudomonas iridis and Pseudo- 

 monas fluorescens exitiosus are also capable of producing the 

 same disease. 



Plants should be taken up and burned on the first indica- 

 tion of the disease. I have found that a liberal use of super- 

 phosphate of lime checks the disease and disinfects the soil. 

 Quicklime favours the disease. The rhizomes of diseased 

 plants should be examined and all soft parts cut away. Neither 



