CHOOSING AND PLANTING. 7 



regular, well-balanced growth ; for those which are irre- 

 gular, one-sided, or cluttered in the branches will never, 

 without care, time, and trouble, develop into trees of 

 elegant form. In young wall or espalier trees, take 

 especial care that the sprays are even and regular. 



A thoroughly healthy appearance in the trees, in bark 

 and foliage, must also be carefully looked to. Never 

 choose any with moss-grown, foul, unhealthy-looking 

 bark, or with American blight, canker, or any other 

 destructive growth, insect, or disease, but notice that the 

 bark is delicate in texture, smooth (according to kind) 

 and clean. 



Canker is an evil which has annually destroyed num- 

 bers of our finest fruit trees, especially pears. It comes 

 from old age, but in young trees it often proceeds from 

 bruises or other ill usage. Trees planted in an uncon- 

 genial soil, and those that are pruned in a bad, slovenly 

 manner, are very subject to the disease. It begins with 

 a swelling of the bark and wood in some one particular 

 spot. In a certain number of years, few or many, ac- 

 cording to the favourable or unfavourable circumstances 

 under which the tree exists, the alburnum (or layers of 

 young wood next to the bark, in which are placed the 

 vessels for the circulation of the sap) perishes, and the 

 bark on the spot cracks, rises in discoloured scales, and 

 decays rapidly, circulation is interrupted, and all the 

 portion of the tree above the canker dies. Take care 

 never to buy trees with an appearance of this disease, 

 nor to induce it by careless bruising and wounding, by 

 allowing branches to cross and chafe each other, by 

 planting in an ungenial soil, nor by humouring an over- 

 rampart growth. 



The American blight is a very destructive aphis which 

 attacks apple trees especially, but other trees also at 

 times. It may be detected in a moment by the appear- 

 ance of a perfectly white cottony matter in the cracks 

 and inequalities of the bark, which form its home. 

 This cottony substance flies on the wind from tree to 

 tree, and so spreads the evil ; and the insect, like other 

 aphides, is said to have wings at its season. 



