124 



ACCIDENTS AND DISEASES OF PLANTS, 



matter generally rests. Now, though we cannot make a soil just as we would 

 wish, still its improvement is within our influence ; and though we cannot 

 change the climate in our neighbourhood, we can at least accommodate our 

 operations to its character. A tree planted in a proper manner, with its 

 collar little, if anything, beneath the surface, in a deep friable loam, resting 

 upon a dry bottom, and where the climate is moderately favourable, will 

 seldom show any sign of canker. Whenever a tree is planted deep, — that is, 

 when the collar is buried a foot or more beneath the surface, — there the 

 canker will be apt to appear, however favourable other circumstances may 

 be. This aptness to canker will be increased almost to certainty, if the 

 ground should be deeply dug, or trenched, and supplied with rank manure 

 near the tree, as then, being forced to obtain its nourishment from a greater 

 depth, it will require a higher temperature and more sunlight to inspissate 

 and elaborate its cmde juices. 



376. To prevent canker^ where good soil is only of very moderate thick- 

 ness, and where the subsoil is a ferruginous gravel, or a stiff cold clay, it is 

 not only necessary to drain the ground and plant upon the surface ; but the 

 trees should be set on the top of mounds from six inches to a foot above 

 the surrounding level, and from four to eight feet in diameter ; the bottom 

 of these mounds being covered with some hard substance, such as stone, 

 slate, &c., to prevent the roots descending, and to lead them out as it were 

 in a horizontal direction. No manure whatever should be incorporated 

 with the soil, unless it should be very poor indeed : but it may be applied 

 as a mulching round the mound, which will tend to keep the roots sufficiently 

 moist and also near the surface. If these points were attended to, w^e should 

 hear little of canker, unless in places naturally very damp, where more 

 than a fair average of rain falls ; or where, from the prevalence of clouds, 

 there is a deficiency of sunshine. In such places the shoots grow so luxu- 

 riantly during summer, that they are yet soft and spongy, and filled with 

 crude juices in the end of autumn. The frost sets in, freezes these juices, 

 bursts the sap-vessels, and the decay of the shoots, or brown blotches, and 

 ultimate canker, are the consequence. The only preventive in such cases is 

 to plant on hillocks, and in soil made light and poor : the wood will then 

 be less luxuriant and better ripened. 



377. What has been said respecting the prevention of canker will also 

 apply to its cure. No scrubbing, scraping, or anointing will be of the least 

 use. Cutting down the trees and allowing them to shoot afresh may be of 

 benefit, if the canker has been produced by one very unfavourable season ; 

 grafting them with hardier sorts will succeed, if the evil arises from unfa- 

 vourableness of climate ; but neither of these methods will be of permanent 

 benefit, when the evil proceeds from soil or deep planting. In such cases, 

 where the trees are very bad, the best method is to destroy them gradually, 

 and plant young ones in a proper manner, leaving some of the old trees until 

 the young ones commence bearing. If the trees are not very old, nor yet 

 too far gone, it will be advisable to take them up carefully, cut away all the 

 cankered wood, plaster up all the wounds with a compound of clay and cow- 

 dung, plant them in fresh soil on hillocks, and give no manure unless what 

 is supplied for mulching. Such trees will generally become quite free of 

 disease and bear splendid crops. A number of years ago, in a large kitchen- 

 garden in the neighbourhood of London, a great number of fruit- trees were 

 dispersed in the different quarters in a miserable state from canker. The 



