CONFERENCE ON SPRAYING OF FRUIT TREES 



359 



to act on all the copper. Care should be taken that the copper sulphate 

 and lime are of the best quality. Many failures are undoubtedly due 

 to the use of bad, impure materials. The mixture should be of a blue 

 colour when properly made and it should be made afresh as required. 



II. The copper sulphate is dissolved in about half a gallon of water, 

 8? 7 gallons of clear limewater is run into this solution, and sufficient water 

 added to make up to 10 gallons. The limewater is made by putting 

 about 7j lb. of quicklime freshly slaked in the way described above into a 

 tub with 12 to 15 gallons of water, stirring once or twice and then 

 allowing to settle. The mixture must be tested as in (I) with potassium 

 ferrocyanide, and if necessary more limewater added until no red colora- 

 tion is given by that test. 



III. Dissolve the copper sulphate in 10 gallons of water and the caustic 

 soda in about 15 gallons. Pour the soda solution slowly into the copper 

 sulphate solution, stir and test the mixture frequently with red litmus. 

 Cease adding soda solution when the red litmus turns blue. The exact 

 amount of soda solution required will vary according to the quality of 

 the caustic soda used. 



IV. Make the copper carbonate into a thin paste with water, add the 

 ammonia, which should produce a clear solution of a deep blue colour. 

 Dilute with water to 45 gallons. 



Uses. — I. Bordeaux mixture is without doubt the best fungicide so far 

 discovered. It is to be used on foliage with the object of preventing the 

 hyphae of the fungus gaining an entrance into the tissues of the leaf, and 

 the aim should be to apply it in such a manner as to cover both surfaces, 

 and especially the under surface, of the leaf with a thin covering as com- 

 pletely as possible. It is useful against scab of apples and pears, brown- 

 rot of plums and other fruits, &c. 



The solution of the strength recommended is often unfortunately too 

 strong, as it is liable to burn young foliage. For spraying young foliage 

 and for some plants at all times the mixture should be diluted with water 

 to about half the strength given in the recipe. 



II. This, or a similar modification of Bordeaux mixture has been in 

 use in Italy, where it has given good results, for many years. It is used 

 for the same purposes as the normal Bordeaux mixture, and the following 

 advantages are claimed for it : — 



" This solution is as efficient as that [Bordeaux mixture] made in the 

 ordinary way, though the latter contains two-and-a-half times as much 

 copper sulphate. It ... is much finer in texture, and, therefore, less 

 liable to settle to the bottom of the liquid ; it also contains no particles 

 of solid lime, . . . and, further, it exhibits its fungicidal action at once 

 after it is applied, instead of necessitating a certain time to elapse before 

 such action begins, as in the case of the ordinary mixture." * 



III. This solution has been used in America, but little in England. 

 It has been spoken highly of in dealing with certain fungoid diseases of 

 the vine, and has the advantage that caustic soda is often more easily 

 procured than good quicklime. It is a solution certainly worth experi- 

 menting with, and may probably be used in the same way as Bordeaux 

 mixture. 



* S. Pickering and P. V. Theobald, Fruit Trees and their Enemies, p. 28. 



