304 



PRINCIPLES OF SPRAYING 



bacteria attacks. The chief spray materials used to prevent dis- 

 ease are Bordeaux mixture, lime-sulfur, ammoniacal carbonate of 

 copper, and livers of sulfur. The first two mentioned are more 

 permanent and are not easily washed off by rains when once dry on 

 the plants. The other two materials are used in cases where it is 

 necessary to wash the fruit or other product before being eaten by 

 people. They may be used to spray fruits that are nearly mature. 

 Another fungicide is copper sulfate used on the dormant form of 



■tmt 



Fig. 212. — Spraying improves quality and increases yield. Sprayed tree at left bore four 

 barrels of apples, 87 per cent marketable. Unsprayed tree at right bore one barrel, only 

 13 per cent marketable. Note also the difference in leaves. (Missouri Station.) 



the plants. Lime-sulfur is also used to control scale insects chiefly 

 during the dormant season of the plants. Each of these will be 

 discussed in this chapter. 



Bordeaux mixture is made of three materials: copper sulfate, 

 fresh lime and water. The standard formula is 4 pounds of copper 

 sulfate, 4 pounds of lime, in 40 gallons of water. This is briefly 

 expressed as 4-4-40. The 3-3-40 formula is sometimes used where 

 plants are tender, as on young tomato plants. 



Dissolve the copper sulfate in hot water or hang the crystals in a 



