mth JRemarJcs on Pruning. 479 



With such success, who would be at the expense of garden 

 walls] for apple trees ; or attend to the theory and practice 

 of pruning recommended by Mr. Harrison (Vol. III. p. 1.), 

 whose system, nevertheless, may be very proper for a northern 

 climate, or for some of the more tender sorts of apples which 

 I am not acquainted with. The cause of the canker in trees 

 is very similar to the cause of the scurvy in man ; it is either a 

 defect of the blood or blood-vessels ; in trees it is generally the 

 defect of the latter, as it is never the ascending sap which 

 causes it, but always the descending sap, which is obstructed 

 in its passage to the root. A wet autumn causes a superabun- 

 dance of sap in the leaves, which, being forced to return in an 

 undigested state, the pores are too contracted to admit it in a 

 regular way, and it forces new channels in the bark; then the 

 first frosty night converts such streams into ice, and they be- 

 come what Mr. Forsyth calls " small dots, as if made with the 

 point of a pin." Midsummer pruning is a good preventive. 

 Trees will sometimes throw out one or two very luxuriant 

 shoots, while the others are quite weakly; by this I always 

 know, that it has thrown out one or two extraordinary luxu- 

 riant roots the previous season. I frequently dig under them, 

 and find the rambler ; if not, I dig them up, and am sure to 

 find it; but this is more common and more vexatious in the 

 walled garden than in the apple orchard ; and I shall, perhaps, 

 talk about it in my next. But I perceive (and, no doubt, you 

 have perceived long ago) that my organ of Descriptiveness 

 is very imperfectly developed. However, I am very happy to 

 see that you have so many able and useful correspondents. I 

 should like to pay a compliment to many of them, particularly 

 to Mr. Dick, for his valuable letter on preserving apples ; it 

 exactly accords with my practice for very many years ; but now 

 I should require, I think, at least two acres of shelves for every 

 acre of orchard, to follow his practice. He is perfectly cor- 

 rect in gathering the fruit before it is fully ripe: neither 

 apples nor turnips will keep, or have so good a flavoui-, if 

 allowed to grow to their full size. The best place for keeping 

 apples is like the best place for keeping ale, viz. a good cool 

 cellar, that is, for such as will keep at all. 



I am, Sir, yours, &c. 



Agronome. 



