atid other Diseases, iii Fruit Trees. 46 1 



all these diseased trees attacked by a grub, which has perforated 

 the stem in every direction, making channels large enough to 

 admit the finger (as you will see by the part of a branch sent 

 for inspection) ; from which, in the summer, extravasated sap 

 exudes, on which wasps and hornets delight to feed. In two 

 or three years after being attacked, the trees, if left to the de- 

 vastations of the grub, will assuredly die. I have for several 

 years observed the wonderful effects produced by grafting some 

 of the new Belgic pears on unhealthy trees, of tender sorts, in 

 transforming them at once into health and productiveness ; and 

 this induced me to try the experiment on those trees which were 

 being devoured alive. I calculated that, if, by some analogous 

 change, the sap could be made healthy, it would also make it 

 unpalatable to these worms of corruption. 



It is now perhaps three or four years since I commenced 

 operations, by grafting on diseased and half-devoured green 

 chisel pear trees, the glout morceau; the autumn, or Williams's, 

 bon Chretien ; Marie Louise, passe Colmar, and other good hardy 

 sorts, and the effect is beyond measure surprising. Trees 

 that must have died in two or three years are now full of health 

 and vigour, and are covered with bloom buds; not a speck of 

 canker or disease is to be seen, and in two years from grafting 

 the grubs left the trees ; the sap having become either too 

 abundant, or too healthy, for their appetites. 



The difficulty is to ascertain, before grafting, what sort of 

 Flemish pear will suit the soil ; for often, after two or three years 

 of deceitful vigour, the graft, if the sort is not hardy enough, 

 will become diseased, and disappoint all expectations. There- 

 fore, before decapitating the old pear trees, advice should be 

 asked on this score ; and I believe that any practical man of 

 observation can at once say what sort will flourish, if you tell 

 him the substratum; though it really seems that many of the 

 Belgian pears will grow and bear in any soil and situation, at 

 least in this southern part of England. 



I am aware that I am advancing no novelty in what follows ; 

 but this sudden change from disease and death to health and 

 vigour is quite worth a moment's consideration, either from the 

 physiologist, or the commercially interested fruit-grower. By 

 giving a tree shoots hardy enough to stand against our cold and 

 moist climate, you give it the only proper and effectual organs of 

 respiration and elaboration; and the consequences are, continued 

 health and productiveness. It is interesting to observe the total 

 reverse of this, if some of the old and tender sorts of apples 

 and pears are allowed to grow, and " have their way," along- 

 side trees grafted with hardy varieties. The shoots of the 

 tender sorts, even the winter after being produced, generally 

 begin to canker and decay : the sap, in spring, losing its proper 



Vol. XII. — No. 78. m m 



