22 MASSACHUSETTS HORTICULTURAL SOCIETY. 



cheapest and most convenient form being the sulphate, commonly 

 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 fungous-spores failed completely to 

 germinate in water containing only 0.03 of one per cent of copper 

 sulphate. If, therefore, a solution containing four pounds of 

 copper sulphate to twenty-five gallons of water, be sprayed upon 

 fungi or their spores, every spore which it touches 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 neighbors to exercise the same sensible 

 precaution. Unfortunately, despite all our efforts, fungi will 

 appear later to some degree. If, when the trees are in full leaf, 

 we should treat them with a solution of the former strength we 

 should indeed prevent fungous attack, but only by destroying the 

 leaves as well. We, therefore, make use of a solution contain- 

 ing three pounds of copper sulphate to twenty-five gallons of 

 water, and further to prevent any possible damage we add to the 

 solution sufficient lime (from two to three pounds, mixed with 

 water to a thin wash) to change all the copper sulphate into 

 the less poisonous hydroxide of copper. We thus get what is 

 known as the Bordeaux mixture, the cheapest and most generally 

 effective of all known fungicides. Others (based upon the 

 solubility of the carbonate of copper in ammonia) , are the simple 

 solution of five ounces of the carbonate in three parts of ammonia, 

 this being subsequently diluted with water to forty-five gallons, 

 and also the modified formula for what is called Eau Celeste, 

 consisting of one pound of sulphate of copper, and one and one- 

 fourth pounds of carbonate of soda, dissolved in one pint of 

 ammonia and diluted with water to twenty-five gallons. These 

 are both clear solutions and therefore do not tend to clog the 

 spraying nozzle as the Bordeaux mixture does when carelessly 

 made with lumps of lime poured into it. Their principal value is 



