2 30 THE LARCH. 



The third form of disease is trunk-eot, sometimes 

 termed dry-rot. It differs from ground-rot in two 

 particulars — first, in the producing cause; and second, 

 in the various forms the disease assumes. Dry-rot is 

 consequent on the tree having exhausted all available 

 food within reach, and being constitutionally too weak 

 to search for more. 



Preventive means. — Planting only such soils with 

 larch as are known to contain the proper elements of 

 food, and sufficient room to spread its roots and 

 branches on all sides, removing the surface turf and 

 soil, especially if rich and damp. 



The signs of this disease are unusual quantities of 

 fruit, smallness of growths, both in the leaders and 

 side branches. The soils which most conduce to this 

 disease are sandy and light, with an unfavourable 

 difference between the condition of the active soil and 

 subsoil. The ground having been under cultivation 

 and manured previous to planting, and the manure so 

 far still present in the soil as to promote a growth in 

 the trees which cannot be longer sustained, conse- 

 quently leaves the tree in a hopelessly exhausted con- 

 dition. 



A fourth form of larch disease is another phase of 

 trunk-rot, in the Highlands of Scotland termed EOY. 

 It differs essentially from the two preceding forms of 

 trunk -rot. It is generally known as matter of fact 

 that the volatile substances of resinous trees undergo 

 various chemical changes during the growth of the 

 tree and maturing of its wood. 



