Fungus Parasites 125 



and water. Cutting out the affected parts and treating the 

 wound as prescribed on page 89, so that a heahhy 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. 

 n/ The best fungicide is the Bordeaux mixture, the formula 

 for which is : — fiye^ppunds 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 



