Fungus Parasites 125 
and water. Cutting out the affected parts and treating the 
wound as prescribed on page 89, so that a healthy callus 
may form, is the especial remedy for black-knot and other 
canker diseases on branches. 
Fungi which attack the leaves are best combated by the 
application of poisons. Like the painting of wounds these 
applications are mainly to prevent the infection by killing 
the spores before they have a chance of sending their my- 
celia into the tissues of the host plant. It is therefore essen- 
tial to make the application in due time, namely, before the 
appearance of the fungus in spring. 
Leaf fungi are, as a rule, not very injurious, the unsight- 
liness which they cause being usually the most objectionable 
result. Nevertheless, since practicable methods are now 
developed of preventing them by fungicides, which can be 
applied at the same time as the insecticides, it is worth 
while to use them, for they benefit the trees in every way. 
The best fungicide is the Bordeaux mixture, the formula 
for which is:— five pounds of copper sulphate (blue vit- 
riol, or blue stone, ten cents per pound), dissolved by being 
suspended in a piece of cheesecloth or a coarse bag in hot 
water; five pounds of fresh (not air-slacked) “quick” 
lime, freshly and slowly slacked, after passing through a 
fine wire (30-inch) strainer, and diluted by adding little 
by little a gallon of water, to a creamy liquid of putty-like 
consistency, free from grit. These two liquid mixtures, 
each in a barrel by itself, are now diluted with twenty-four 
gallons of water each. They are then slowly mixed by being 
poured simultaneously into a fifty-gallon cask. This is the 
“five, five, fifty’ formula. No iron or tin vessels should be 
used in preparing this mixture and, of course, care should be 
taken not to burn the clothes or fingers in the handling of 
both the blue stone and the lime. The lime is added to 
