60 



free it of superabundant moisture — the canker, under 

 any one of these circumstances, is almost certain to 

 make its appearance amongst the trees they sustain, 

 however young and vigorous they were when first 

 planted. 



How inductive of this disease is a wet retentive sub- 

 soil, if the roots penetrate it, appears from the state- 

 ment of Mr. Watts, gardener to R. G. Russell, Esq., 

 of Chequer's Court, in Buckinghamshire. A border 

 beneath a south wall had a soil three feet and a half 

 in depth, apparently of the most fertile staple, twice 

 re-made under the direction of the late Mr. Lee, of 

 the Vineyard, Hammersmith. In this the trees, 

 peaches aud nectarines, flourish for the next three or 

 four years after they are planted, but are then rapidly 

 destroyed by the canker and gum. The subsoil is a 

 stiff sour clay, nearly approaching to a brick earth ; 

 and the disease occurs as soon as it is reached by the 

 roots of the trees. * 



Mr. Forsyth concluded that the soil is not always 

 the source of the disease, because it universally and 

 invariably appears at first in the branches, and pro- 

 ceeds thence towards the roots of the tree. But this 

 is certainly not a conclusion warranted by the pre- 

 mises, because the acridity of the sap, whatever may 

 be its source, would be likely to injure and corrode, 



* Gardener's Magazine, vi. 617. 



J 



