TREE Roor DISEASES. 1. 


is practically outside the question when a plant is once per- 
meated with mycelium; and keeping in view the varied 
modes of reproduction for facilitating the rapid spread of the 
disease, no efforts should be spared in the way of prevent- 
ing such spreading, when the presence of the fungus is 
once detected. 
Undoubtedly the most frequent and rapid mode of 
spreading is by means of the mycelium travelling in the 
soil, and a good method of isolating diseased patches is to 
cut a narrow trench, from nine inches to a foot deep, 
round such, care being taken to throw the excavated soil into 
the diseased portion, and not outside of it. This method, 
which was first suggested by Hartig for the purpose of pre- 
venting the spread of subterranean fungi in the German 
forests, cannot be too strongly commended, especially where 
the diseased patches are small in area. The amount of 
success depends entirely on the thoroughness, combined with 
an intelligent method of carrying out the work. Half 
attempts invariably result in a loss of capital without 
benefit. It may be enough to suggest that the disease may be 
spread by the spores of the fungus, or infected soil being 
carried by the shoes of labourers, by dirty tools, wheels of 
carts, animals, etc., from diseased centres. Diseased and 
fallen trees, and especially stumps and roots, should be at 
once destroyed by burning. The soil surrounding diseased 
stumps should be burned after the stumps have been 
removed, so as to destroy the smaller diseased portions of 
the root that remained behind. __ 
f. second preventive method, which has proved of service 
in France, is to lay bare the trunk as far below the surface of 
the soil as can be done without injury to the tree, and to 
densely coat the expused trunk and adjoining soil with 
powdered. sulphur. This should be repeated when the 
channel round the trunk becomes filled up with earth. I, 
as stated by Mr. Wight, the New Zealand fungus first attacks 
the trunk just below the surface of the soil, this method 
should prove beneficial if persevered with. 
Stagnant water should not be allowed to remain in the 
soil, as this favours the spread of the fungus. 
