SUMMER MEETING AT OREGON. 161 



We come now to the third method, that of applying to the vines a 

 substance which will destroy the germs or prevent them from gaining 

 access to the interior of the fruit. Many chemicals have been recom- 

 mended and used for this purpose, but so far none have given very satis- 

 factory results. The only substance which gives promise of value in this 

 direction is sulphate of copper or blue stone. A very small quantity of 

 this substance is sufficient to prevent the spores of the black-rot fungus 

 from germinating, and if by some means the leaves and the fruit are 

 covered with a thin film of the substance, it is very probable that the 

 spores will be destroyed before they are able to seiid their germ-tubes 

 into the tissues. Both in this country and Europe, during the past two 

 years, extensive experiments have been carried on with copper com- 

 pounds in the treatment of black-rot and other diseases of the vine. While 

 these experiments have not clearly demonstrated the value of copper sul- 

 phate as a preventive of black-rot, there is sufificient evidence at hand to 

 warrant us in saying that the use of this substance should be continued 

 at least until more positive results are obtained. 



The sulphate of copper may be applied to the vines in various ways. 

 Many have used a simple solution made by dissolving one pound of sul- 

 phate of copper in twenty-five gallons of water. This preparation, how- 

 ever, has not given very satisfactory results, and frequently the foliage 

 has been injured by it. So far, the following compounds of copper and 

 lime have proved most satisfactory, their effects being far more lasting 

 than those obtained by the simple solution. 



LIQUIDS. 



1st. Copper mixture of Gironde, Bordeaux mixture, original 

 formula: " Dissolve i6 pound of sulphate of copper in 22 gallons of 

 water; in another vessel slake 30 pounds of lime in six gallons of water; 

 when the latter mixture has cooled it is slowly poured into the copper 

 solution, care being taken to mix the fluids thoroughly by constant 

 stirring. It is well to have this compound prepared some days before it 

 is required for use. It should be well stirred before applying. 



MODIFIED FORMULA. 



Sulphate of copper 4 lbs. 



Lime 4 lbs. 



Water 22 gals. 



u. K. — II. 



