«72 Agricultural Gazette of N.S.W. [Sept. 2, 1920. 



How the Disease is Spread. 

 The means by which the disease spreads are as follows : — • 



1. The fungus, which is a parasite on native timbers, is left over on 



stumps and in the soil when the land is cleared for planting, and 

 the young trees are too often planted befoi'e the pest has died out. 



2. By means of infected roots coming in contact with the extremities of 



adjacent trees. 



3. By means of spores, which are shed from tlie gills on the underside 



of the cap of the toadstool or sporophore. 



Eifect of the Fungus on the Tree. 

 The fine fungus threads penetrate the tissues of the root and form a fungal 

 sheet, resembling a sheet of tissue paper, between the wood and the bark 

 ^Fig. 4), This robs the root of nourishment, and prevents the rising of 

 nourishment to the stem, the result being that the tree gradually perishes. 

 The cutting off of the sap supply produces a yellowing of the leaves and 

 prevents the manufacture of the food necessary for the maintenance of the 

 tree. The presence of the fungus between the wood and bark also i)revents 

 the formation of new wood and bark tissue. In advanced cases the butt 

 of the tree may be ringbarked by the fungus. 



Control Measures. 



It is hardly possible to adopt effective control measures, but it is desirable 

 that every means possible be taken to get rid of all stumps and roots before 

 an orchard is set out. In districts where the pest is known to exist, newly 

 cleared land should be sown to some grain or other field crop (with the 

 exception of potatoes, which are susceptible) for several years previous to its 

 use for orchard purposes. 



When a tree is found in the early stages of attack, the soil should be 

 removed from the butt and main roots, the diseased bark at the butt removed 

 ■with a sharp knife, and all diseased roots traced out as far as possible and 

 removed. The cut surfaces should be painted with bluestone paste, made as 

 follows : — 



Sulphate of copper (bluestone) ... ... l|lb. 



Quicklime... ... ... ... ... 4 ,, 



Water IJ gals. 



Dissolve the bluestone in portion of the water and the lime in the 

 remainder, and then mix both together to form the paste. 



It is recommended that, when replacing the soil, a fair proportion of the 

 root-sj'stem be left uncovered (say one foot from the butt all round) iov an 

 indefinite period. All diseased material and toadstools should be burnt. 



Where possible the affected trees should be isolated by digging a trench 

 2 feet deep around them, such trench to be outside the spread of the root- 

 •systems. All soil removed in the operation should be thrown on the inside 

 of the quarantined area. Trees found in an advanced stage of the disease 

 should be immediately removed, as they are beyond treatment and are a 



