CAN 



CAN 



disease, from the buds of trees being a lateral 

 progeny, and consequently having a more exact 

 resemblance to their parents, "being thereby 

 " more liable to the diseases gradually acquired 

 or increased by the influence of soil or climate;" 

 not having the probability of improvement, as 

 in those propagated in other modes. 



The disease is, however, capable of being 

 produced in other ways. It is very apt to be in- 

 duced in different soils of trees by the destruc- 

 tion of the bark, by external violence, as a blow 

 of the spade where digging is performed without 

 sufficient caution. 



In apple-trees Mr. Forsyth has found it very 

 liable to be caused by the want of due attention 

 in pruning, the leaving of the foot-stalks of 

 the fruit on the trees; and certainty b; 

 bruises produced by ladders in gathering the 

 fruit. Too tight nailing, from the pressure of 

 the shreds on the shoots. The the 



autumn season, by preventing the wung wood 

 from becoming well ripened, wh Jed 



bv sharp frost, often produces the disease, from 

 the young shoot being destroyed and left on the 

 trees. Their being left in this way has like- 

 wise much tendency to promote its increase. 

 It is also suggested that the buds' being eaten and 

 destroyed by birds or insects produces the same 

 consequences. 



Mr. Forsyth well remarks, that by leaving 

 the dead wood on the trees during the summer, 

 the disease is infallibly brought on; and that 

 when it is continued for years they are wholly 

 destroyed. He advises their being cut off the 

 latter end of April, or in the following month, 

 when their progress can be ascertained, and to 

 perform the operation three, four, or more buds 

 below the seemingly diseased part, as the affec- 

 tion often extends much further in the heart of 

 the shoot, than it seems to do on the outside. 

 The cutting should be carried so far down that 

 the rusty colour disappears, and there is only the 

 sound white wood. 



Some contend that this disease is produced in 

 all sorts of trees, solely by the quality of the 

 soil, as where it is of the sour clayey, shingly, 

 or gravelly kind; but Mr. Forsyth found that in 

 these, though he allows that fruit-trees succeed 

 best in mellow loams, the roots were not in the 

 least affected where the branches were very 

 greatly diseased. It is asserted that the canker 

 constantly proceeds from the branches and stem 

 to the roots, but never in the contrary direc- 

 tion. 



When trees are very much affected in conse- 

 quence of large wounds, it is advised, by the 

 above writer, to pare off all the infected parts of 



the bark with a draw-knife; and as the inner 

 white bark is frequently diseased, having a 

 dotted appearance, it should likewise be wholly 

 removed, as, when anv is left, it extends itself 

 afresh. And when the trunk is become hollow 

 it is recommended to round out. the decayed 

 parts, and then to apply the composition which 

 he has recommended in a liquid state, with a 

 brush, over the parts from which the cankered 

 bark or dead wood has been removed, shaking 

 the powder of wood-ashes and burnt bones over 

 i'. In this way the disease will soon be re- 

 in ved, aud the hollow trunk in time filled 



U P' 



But when the stem is greatly decaved it is 



v i open the earth, and remove all the 



rotten parts completely ; then filling up the 



parts with a mixture of the composition and 



clay, as used ia grafting, to within a few inches 



of the surface ground, forcing it well in by 



treading, the surface being made sloping from 



the tree, to convey off the wet. The whole 



should then be made level with mould. 



After having managed the old wounded parts 

 in this way, the old bark is advised to be exa- 

 mined, and, when found wrinkled or cracked, 

 on the outside, pared off with a draw-knife, 

 and the composition applied as above ; which 

 produces a fine smooth hark underneath it, the 

 plaster with the old bark peeling off in the suc- 

 ceeding winter or spring ; at this time, all the 

 old bark remaining in the hollows, being re- 

 moved by a wooden or bone knife. After this, 

 the parts from which the bark has been scraped 

 off should be thinly coated over with a liquid 

 composed of cow-dung, soap-suds, and urine. 

 This remains till the new bark is formed, when 

 it is discharged of itself, during the summer or 

 following spring, leaving a fine new smooth 

 bark. The same operation may be repeated in 

 the ensuing spring if there should be occasion ; 

 by which the whole of the old diseased bark 

 may be sloughed off, and the tree kept in a fine 

 healthy state and perfect order. 



In the prevention of this vegetable affection, 

 much care is necessary in the pruning and other 

 management of the trees. All the ends of 

 diseased shoots should invariably be removed, 

 as well as the old fruit-stalks and dead stubs 

 cut away. The appearance of gum on the 

 stems or branches of trees indicates their being 

 attacked with the canker. 



Common white paint is sometimes made 

 use of as an application for the removal of 

 canker. When this substance is employed, 

 Dr. Darwin has suggested that it may pro- 

 bably be rendered more destructive to insects, 



