702 



PRACTICE OF GARDENING. 



PART III. 



and (c), made by cutting out the cankery part, and which being covered with the com- 

 position were soon nearly filled up with sound wood. Very little pruning is at first given 

 to trees so cut, but afterwards a regular succession of bearing wood is kept up by re- 

 moving such as have borne for three or four years. Thus, one branch (d), which has 

 done bearing, is cut off, and succeeded by another (f\ and when that is tired also, it is 

 cut off, and replaced by a third (e), and so on. 



4429. Grafting old apple-trees pf different sorts with superior varieties, is an obvious and long-tried im- 

 provement. In this case, if the tree is a standard, it is only headed down to standard height ; in old sub- 

 jects, most commonly the branches only are cut over within a foot or two of the trunk, and then grafted 

 in the crown or cleft manner. 



4430. Injuries, insects, &c. The mistletoe (Viscum album} is frequently, through negligence, suffered to 

 injure trees in orchards, and different species of mosses and lichens those in gardens. " Moss," Knight 

 observes, " appears to constitute a symptomatic, rather than a primary, disease in fruit-trees : it is often 

 brought on by a damp or uncultivated soil, by the age of the variety of fruit, and by the want of air and 

 light in closely planted unpruned orchards. In these cases it can only be destroyed by removing the cause 

 to which it owes its existence." 



4431. Blights. Whatever deranges and destroys the organisation of the blossom, and prevents the set- 

 ting of the fruit, is in general termed a blight ; whether produced by insects, parasitical plants, or an 

 excess of heat or cold, drought, or moisture. One of the most injurious insects with which the apple- 

 tree has been visited for the last twenty years, is the Aphis lanigera, L., the Eriosoma mali of Leach ; 

 woolly aphis, apple-bug, or American blight. " The eriosomata," Leach observes, " form what are 

 called improperly galls on the stalks of trees, near their joints and knobs, which are in fact excrescences, 

 caused by the efforts of nature, to repair the damage done to the old trees by the perforation of those in- 

 sects whose bodies are covered with down." (Sam. Ent.) Salisbury has given an engraving of the erio- 

 soma (fig. 485.) as he found it appear under a magnifying glass, when attacking the roots (a) and the 

 branches (6), as well as a still more highly magnified figure of one of the bugs without wings (c) and 

 winged (d). The latter he considers likely to be the male insect. Thoroughly cleaning with a brush and 



485 



