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tions used as fungicides. It was there shown that, in the spraying of large orchards, 

 a considerable quantity of copper sulphate was used annually, and it was maintained 

 that this would accumulate in the soil — as it all eventually tinds its way there — and 

 finally there was very great danger that this would sterilize or render barren the 

 soil. 



At the request of several correspondents, who were anxious to know how far 

 these statements were correct, I made a report thereon, the substance of which I 

 now insert as affording some information to orchardists on this important subject. 



Properly applied, i.e., at the right time and in the correct proportions, the 

 copper fungicides have proved and are proving themselves to be of inestimable ben- 

 efit in the orchard and in the vineyard. The increased value of the fruit has more 

 than repaid, by a large margin, the outlay for spraying apparatus and materials and 

 cost of application, and I believe the time has come when no fruit-grower can afiord 

 to ignore this useful means of preventing fungus diseases. Not the least important 

 element in successful fruitgrowing, now-a-days, is keeping in check fungus growths 

 and destructive insects, and, for this purpose, our present hope lies in the applica- 

 tion of arsenical and copper solutions. By the more extended use of them the hope 

 is confidently entertained that the loss occasioned by injurious insects aud fungi will 

 be greatly lessened year by year throughout the Dominion. 



The danger to the fertility of the soil by the use of fungicides has, by some, 

 been unduly magnified. In the first place, the large quantity of fungicides as re- 

 commended heretofore for each acre of trees per annum (400 gallons containing 108 

 lbs. of copper sulphate)* is considered by many of the best authorities as unneces- 

 sary. Three or four sprayings are equally efficacious with a larger number, pro- 

 vided the operation is begun early enough in the spring. Granting that each appli- 

 cation requii-es, per acre, about 30 gallons, the total quantity of Bordeaux mixture 

 per acre for the season would be between 90 and 120 gallons, containing from 24J 

 lbs. to 32^ lbs. of copper sulphate. 



Secondly, Bordeaux mixture has to a very large extent been replaced by copper 

 carbonate, either dissolved in ammonia — known then as ammoniacal copper caroon 

 ate — or applied simply in suspension. When applied in suspension or dissolved, 

 the amount of copper carbonate per 25 gallons of water is two ounces — a quantity 

 containing the same amount of copper as four ounces of copper sulphate. (Dii-ec- 

 tions for preparing these solutions are to be found in Bulletin 10 of the Experimental 

 Farm series.) Spraying with the fungicides, each acre of vines would receive during 

 the season the equivalent of 1 lb. to 1^ lbs. of copper sulphate. It is thus made mani- 

 fest that by this treatment — one highly recommended by those who have had exper- 

 ience with it — no such quantity as 108 lbs. of copper sulphate is required per acre. 



By far the greater amount of copper that reaches the ground is in a condition 

 that is insoluble in water, or becomes so after a short time. In the case of Bordeaux 

 mixture, I would point out that copper sulphate, as such, ceases to exist imme- 

 diately after the addition of the lime, sulphate of lime (land plaster) and an insoluble 

 compound of coppei* resulting. The argument, therefore, that the sulphuric acid of 

 the copper sulphate immediately combines with the potash of the soil, which is sub- 

 sequently lost, does not hold good. The sulphate of lime does, to a limited extent, set 

 free potash in the soil, in a condition assimilable by plants, and on account of this 

 benericial function land plaster is often used as a fertilizer. The presence of minute 

 quantities of an insoluble copper compound cannot, in my opinion, affect disastrously 

 the fertility of a soil, nor act as a poison to plants. The acid fluids secreted by root- 

 lets may have the power of rendering such soluble and thus capable of absorption, 

 but unless the soil were heavily charged with copper compounds no evil effects from 

 this cause need be anticipated. Plants can only absorb into their tissues fluids and 

 gases, and although they have ihe power to a limited extent of rendering soluble 

 certain substances, insoluble compounds, such as oxide and carbonate of copper, are 

 for the most part harmless and inert. 



* Bordeaux mixture contains 6 lbs. copper sulphate and 4 lbs. of lime in 22 gallons of water. The lime 

 aeutraliz«a 6ha caustic effect of the copper sulphate, rendering the mixture innoxious to foliage. 



