232 PYRUS COMMUNIS. 
From the pyramidal, and often fastigiate form of the pear, its summit requires 
much less space than the apple or the cherry. In the more fertile soils, the dis- 
tance at which the trees may be planted apart, need not exceed twenty feet ; and 
those of a poorer soil may be much less. The quenouilles, or dwarfs, trained in 
the form of a distaff, with their branches reaching nearly ox quite to the ground, 
are found to succeed even at a distance of four or five feet apart, and produce 
abundant crops. 
The pear-tree is liable to be much injured if pruned by those who do not 
understand the nature of its growth. The blossoms are commonly produced 
from buds at the extremity of the last year's shoots, and as these are often cut 
off by the unskilful primer, it prevents them from producing fruit, and causes 
the boughs to send out new branches, which overfill the tree with wood. For 
reasons assigned on the subject of pruning in our articles on the cherry and plum, 
July and August is the best time to look over the pear-trees, and to remove all 
superfluous and foreright shoots, which would too much shade the fruit. 
The rate of growth of the cultivated pear-tree, in Britain, is considered, on an 
average, as from two to three feet per annum, for the first six or seven years ; in 
ten years it will acquire the height of twenty feet ; and in thirty years, it will 
attain an elevation of fifty feet, with a trunk from one foot to eighteen inches in 
diameter. Its development or rate of growth, in America, under favourable cir- 
cumstances, is equal to that of Europe, and in some instances, even surpasses it. 
Accidents, Diseases, and Insects. " The pear, as a standard tree," says Mr. Lou- 
don, " is not liable to have its branches broken off or disfigured by the wind ; nor 
is it nearly so liable to canker as the apple-tree. It is liable to the attacks of insects, 
but certainly not so much so in fields as in gardens, and perhaps nowhere to the 
same extent as in the other edible fruit-bearing Rosacea?. On a large scale, there 
is. perhaps, no cure worth attempting, for insects, or mildew on the leaves; but 
shallow planting, surface manuring, and regrafting, are excellent preventives and 
correctives for these and all other evils to which the pear, and all other Rosacea?, 
are liable." In Britain, the leaves of the pear-tree are affected by a species of 
fungus, (JEcidinm cancellation, Sowerby,) which, in moist seasons, and in close 
situations, sometimes appears to so great an extent, as to occasion them to fall 
prematurely. There seems to be no remedy, except that of increasing the airi- 
ness of the situation, which may always be done, to a certain extent, by thinning 
out the branches of the tree. The trunks of cankered trees, in Europe, are some- 
limes perforated in every direction by the larva? of the lesser stag-beetle (Dorcns 
parallelopipedus, Stephens.) In Europe, also, the larva? of the wood leopard-moth, 
(Zeuzera cescidi, Latreille,) also perforate longitudinally the trunk of the pear- 
tree, as well as that of the apple, the service, the quince, and probably those of 
all the Rosacea?, as it is known to do in the horse-chesnut, lime, walnut, beech, 
birch, and oak. 
In America, the pear-tree is subject to a peculiar malady, called the blight, 
which shows itself during midsummer, by the sudden withering of its leaves and 
fruit, and the discolouration of the bark of one or more of the limbs, followed by 
the immediate death of the part affected. From a communication in the fifth 
volume of the " New England Farmer," by the late Judge Lowell, of Roxbury, 
in Massachusetts, it appears that this malady is caused by the larva? of an insect, 
named by Professor Peck, Scolytus pyri. They eat their way inward through 
the alburnum, into the hardest part of the wood, beginning at the root of a bud, 
(behind which, Dr. Harris thinks the eggs are deposited,) following the course 
of the eyes of the buds towards the pith, around which it passes, and part of 
which it also consumes ; thus forming, after penetrating through the alburnum 
or sap-wood, circular burrows or passages, " not exceeding the size of a knitting- 
needle." in the heart-wood, contiguous to the pith which they surround. By 
