391 



Plant Sanitation. 



This mixture can be used successfully on many plants, but on others, like 

 the peach and Japanese plum, it injures the foliage. It also sometimes russets the 

 fruits of apples and pears. It can be increased in strength for certain purposes 

 by reducing the proportion of water, but the formula given above has been regarded 

 as the standard with which all others should be compared, at least in experi- 

 mental work. 



77 l(? 5_5_5o Formula.— Standard Bordeaux mixture is frequently slightly 

 modified ; a very common modification being made according to the formula 

 which follows : 



Copper sulphate ... ... ... ... pounds 5 



Lime ... ... ••• ... ■•■ do 5 



Water to make ... ... ... ... gallons 50 



The use of this formula is desirable where the purity of the lime is in doubt, 

 as it makes certain, with lime of any reasonable quality, that all of the copper is 

 properly neutralized. The danger of scorching or russeting the fruit is therefore 

 less. Withholding one pound of copper sulphate also cheapens the mixture by 

 a few cents. For these reasons the 5—5—50 formula has come to be quite generally 

 used in orchard spraying. In fact, it has almost replaced the old standard Bordeaux 

 mixture in spraying for the apple scab, bitter-rot, pear and cherry leaf-blight 

 and similar diseases. In the central Mississippi Valley the 4—5—50 formula has 

 given good results, especially in dry years. 



The 4—4—50 and other Formulas.— The strength is often still further reduced 

 by using a 4—4—50 formula, but it is questionable whether it pays to reduce the 

 strength. The same result can be secured with sprays having less copper, provided 

 the application is thorough and repeated ; but, as in actual experience the cost of 

 applying Bordeaux Mixture is often from two to five times the cost of the mixture 

 itself, economy demands the use of the strongest mixture which will do the work 

 without injury to the plants. 



For use as a whitewash, a very concentrated mixture, 6—4—20 may be 

 desirable ; and for certain diseases Bordeaux mixture can be diluted so as to be 

 equivalent to 6—4—100. 



Peach Bordeaux Mixture.— The form of Bordeaux most harmless to foliage 

 is made up by the formula 3—9—50, having a considerable excess of lime. This may 

 be known as " Peach Bordeaux mixture," and contains ingredients as follows : 

 Copper sulphate ... ... ... ... pounds 3 



Lime ... ... ... ... ... do 9 



Water to make ... ... ... ... gallons 50 



Modified Bordeaux Preparations. — Various modifications of the original 

 mixture have been suggested and tried. The principal ones, however, are the 

 "Soda Bordeaux mixture" and the "Potash Bordeaux mixture." The former 

 consists of six pounds of copper sulphate, 2 pounds of caustic soda, and 50 gallons 

 of water. The latter is the same except that an equal quantity of caustic potash 

 is substituted for the soda. Other materials are sometimes added to Bordeaux 

 mixture to increase its spreading power. The most successful is ordinary hard 

 soap, dissolved in hot water and added at the rate of four pounds to the barrel, and 

 this modified Bordeaux mixture is known as " Soap Bordeaux." 



METHOD OF MAKING BORDEAUX MIXTURE IN SMALL QUANTITIES 



Where only a small quantity of Bordeaux mixtme is required— from a 

 bucketful to a barrel— the method described by Dr. B. T. Galloway in Farmers' 

 Bulletin, No. 38, gives excellent results. Two half-barrel tubs are made by sawing 

 a barrel through the middle. One tub is used for the bluestone solution and the 

 other for the milk of lime, and each tub should contain 23 to 25 gallons. One man 

 dips the bluestone solution with a bucket and pours it into a barrel or other 



