CH. VIII.] THE DISEASES OF PLANTS. 285 



the varieties of the apple which I have found in the 

 catalogues of the middle of the seventeenth century, 

 are unproductive of fruit, and in a state of dehility 

 and decay. "^ 



Among the individuals particularly liable to be in- 

 fected, are those which have been marked by an ex- 

 cessively vigorous growth in their early years. I had 

 one in my garden at Great Totham, which for the first 

 twelve years of its existence was remarkable for the 

 unnaturally large size and abundance of its annual 

 shoots. It then became grievously affected by canker 

 which at length destroyed it. 



Trees injudiciously pruned, or growing upon an 

 uugenial soil, are more frequently attacked than those 

 advancing under contrary circumstances. The oldest 

 trees are always the first attacked of those similarly 

 cultivated. The golden pippin, one of the oldest 

 existing varieties of the apple, is more frequently 

 and more seriously attacked than any other. 



The soil has a very considerable influence in 

 inducing the disease. If the subsoil be a ferruginous 

 gravel, or if it is not well drained, and the soil be 

 aluminous, and effective means are not adopted to 

 free it of superabundant moisture — the canker, under 

 any one of these circumstances, is almost certain to 

 make appearance amongst the trees they sustain, 



* Some doubts as to the Efficacy of Mr. Forsyth's Plaster, by 

 T. A. Knight, Esq. P. L. H. S., &c., 1802. 



