64 
THE APPLE. 
In a word, canker comes througli many channels, the chief of which 
are doubtless an unsuitable soil, an ungenial climate, extreme and 
sudden changes of condition, unseasonable frosts, and insect pests. It 
may generally be prevented, seldom wholly cured. The favourite remedy 
used to be to cut out canker ; and to some extent the remedy was 
successful. The strong growths that followed severe prunings continued 
free for a time, but they generally succumbed to canker in the end. 
At times canker seems developed from the action of lichens on the stems 
or branches. In such cases a thorough cleansing and a smearing of 
quick lime made into a wash proves useful. A wash of strong tobacco 
water or a weak solution of sulphuric acid is also fatal to lichens and 
mosses, and, so far as they destroy the latter, prevent canker originating 
in that way. But, in general, canker may be almost held to be incurable, 
and the best and safest course is to avoid, as far as possible, every 
producing cause of this troublesome and, some hold, infectious disease. 
IL-Mildew. 
Mildew, even more than canker, is a proof of an ungenial site or 
mismanagement somewhere. A wet soil or subsoil, an excess of manure, 
a deficiency or an excess of water, or any sudden check, will also, at 
times, produce mildew. Overcropping by exhausting the trees also some¬ 
times invites or aggravates this troublesome disease. Sulphur dressings, 
or dredgings with equal parts quick lime and dry sulphur are useful 
checks to the ravages of mildew •, but drainage, a renewal of the soil, 
or surface planting on raised hillocks, or an entire change of site are the 
only radical cures. 
I 
TIL—American Blight. 
The American blight is both a disease and an insect pestof the very 
worst description. This is at once the most mischievous and difficult to 
eradicate of all apple pests. It attacks the tree at all points, root and 
branch—strong trunk or delicate twig—gnarled bark and juiciest young 
wood—no part, above or below ground, is safe from the ravages of 
the American blight. It resembles at first sight a short tuft of fine 
cotton wool, slender as finest threads, laid into the crevices of the 
bark, or arranged in tufts around the buds or gnarled knots on the 
stem. On examination it is found that these flowing filaments are but 
the external fringes of hosts of wingless insects that prey upon the 
juices of the tree, and, in consequence, produce gouty-like excrescences 
on root and branch that destroy their tissues, and not seldom sacrifice 
