i INTRODUCTION 11 



make up the 50 gallons, the resulting Bordeaux mixture will be 

 of very inferior quality. 



The method of mixing described above is that recommended 

 by all scientific authorities in the United States and in our 

 Colonies. Bordeaux mixture prepared by growers in accordance 

 with these instructions has long proved in these countries to 

 be of the greatest value, under practical conditions in the 

 orchard and plantation, in keeping off fungus pests from 

 cultivated plants. According, however, to the recent important 

 investigations of Mr. S. U. Pickering into the nature of 

 Bordeaux mixture, a slightly superior method of mixing the 

 two constituents is " to take the lime in as weak a condition 

 as possible and, consequently, the copper sulphate in as strong 

 a condition as possible, and to add the copper sulphate to the 

 lime. The ' milk-of-lime,' after being diluted with the bulk of 

 the water and stirred up several times during about half an 

 hour, should be left for the grosser particles to settle before 

 the copper sulphate is added to it, and, after the addition of this, 

 very little more stirring should be done." 



Bordeaux mixture is fully efficacious only when freshly 

 made, and will not keep. If more than a day old, it requires to 

 be very thoroughly and constantly stirred while being used, 

 and the use of only freshly -made Bordeaux mixture is far more 

 economical in the long run, and is here strongly recommended. 



If a considerable quantity of Bordeaux mixture is required 

 for use, the making of stock solutions of copper sulphate and 

 lime, which can be kept through the spraying season and used 

 when wanted, saves both time and labour, and is free from all 

 objections. The stock solutions are made as follows: take 

 two 50-gallon barrels. In one dissolve 50 Ib. of copper sulphate 

 in exactly 50 gallons of water. In the other slake 50 Ib. of 

 lime by the gradual addition of a little water ; to the creamy 

 paste thus obtained add water to make exactly 50 gallons of 

 "milk-of-lime." These stock solutions will keep for months. 

 Before the "milk-of-lime" is used, the contents of the barrel 

 must be thoroughly stirred, as the slaked lime will have sunk to 

 the bottom. (Care must be taken to stir the "milk-of-lime" 

 very thoroughly each time before measuring it out, so as to get 

 the slaked lime thoroughly in suspension. If this is done there 

 is no difficulty in obtaining the correct quantity of lime per 

 gallon of fluid.) Each gallon which is taken out from the 

 "stock solutions" will be equivalent, respectively, to 1 Ib. of 

 copper sulphate or 1 Ib. of lime. The required amount of each 

 stock solution is then diluted with water, according to the 

 formula given above, before being mixed together. The " stock " 



