No. 4.] FUNGOUS DISEASES. 93 



and second alone are adapted to field work, while the third is 

 invaluable in the greenhouse or any enclosed space. Let us 

 consider first the liquids. 



The salts of copper exercise, when applied in sufficient 

 quantity, a most harmful efiect upon all vegetation, the 

 cheapest and most convenient form being the sulphate, com- 

 monly known as " blue vitriol." The delicate nature of 

 fungi renders them peculiarly susceptible to the action of 

 this chemical, recent laboratory experiments which I have 

 been conducting showing that comparatively resistant fun- 

 gous spores failed completely to germinate in water contain- 

 ing only .03 of one per cent of copper sulphate. If, there- 

 fore, a solution containing one pound of copper sulphate to 

 twenty-five gallons of water be sprayed upon fungi or their 

 spores, many of the latter will be killed. We act upon this 

 principle in our preliminary or winter spraying. In March 

 or early April, before the buds have begun to swell, we give 

 the trees and the subjacent ground a thorough spraying with 

 a simple solution of copper sulphate made in the proportions 

 just mentioned. The spores which have developed in the 

 refuse lying on the ground, or which have lodged in the 

 cracks and crevices of the bark, are thus largely destroyed. 

 We start with our orchard or garden comparatively free from 

 the germs of disease, and have only to persuade our neigh- 

 bors to exercise the same sensible precaution. Unfortu- 

 nately, despite all our efforts, fungi will appear later to some 

 degree. If, when the trees are in full leaf, we should treat 

 them with the strong solution of copper sulphate, we should 

 indeed prevent fungous attack, but only by destroying the 

 foliage. It is therefore necessary, at this stage, to lise some 

 other salt of copper, preferably an insoluble one. Fort- 

 unately, it is a simple matter to transform copper sulphate 

 in solution into the insoluble hydrate of copper, by merely 

 adding to it a whitewash made of ordinary stone lime. If 

 enough of this is added, all of the sulphate is changed to the 

 hydrate, which remains suspended in the liquid. This is 

 the famous Bordeaux mixture, the most generally useful of 

 all known fungicides. The simplest method of preparation 

 is as follows : Dissolve five pounds of granulated copper 

 sulphate in twenty-five gallons of water. Slake five pounds 



