394 STATE BOARD OF AGRICULTURE. 



The first injury was due to heavy late frosts occurring while the foliage was 

 still very young. The damage, however, was considered unimportant, and of 

 course beyond control. 



Injury to foliage of apples by spraying was noted as 'quite general in New York 

 during the summer of 1902. The foliage appeared spotted and yellowed and 

 eventually fell off. The trouble was not considered as due to the use of improper 

 spraying materials so much as to the tender condition of the foliage during that 

 season induced by the protracted cold, wet weather. 



Occasional injuries of this nature should point to the use of proper care ia 

 spraying methods and not to the abandonment of spraying. 



SPRAYING AND SPRAY MATERIALS. 



From the time of the discovery in France in 1883 that a mixture of lime and 

 copper sulphate, applied with a whisk broom, would check the ravages of the 

 downy mildew of the grape, to the present use of fungicides, applied with power- 

 ful pumps and perfected spraying nozzles, a long stride has been made in the 

 prevention of plant diseases. And yet at the end of twenty years, during which 

 a great many formulas have been devised and tested, copper in some form still 

 retains its place at the head of the list of fungicides. Moreover the combination 

 of copper sulphate with lime first used, and which soon became known as Bordeaux 

 mixture, is still the most popular and widely used preparation of the copper 

 salts. 



The chief value of a spraying mixture lies in its ability to prevent the germina- 

 tion of the spores of the parasitic fungi causing diseases. Thus a condition of 

 immunity is secured to the plant while it is covered with a layer of the fungicide. 

 The salts of copper which have been found to be preeminently fungicidal owe 

 their extensive use in this line to the fact that when they are present, even in 

 seemingly insignificant amount the spores of fungous diseases are either pre- 

 vented from germinating or killed when germination begins. Sulphur, both free 

 and in the form of powder or in combination with other elements, is also capable 

 of checking the action of the surface mildews for which purpose it has long 

 been used. 



in order that the best possible results may follow the use of any spraying 

 mixture, the following conditions should be aimed at, — 1. The fungicide should 

 be the one most effective for the prevention of the disease to be combated. 2. 

 The spraying mixture should be harmless to the foliage and other organs of the 

 plant treated. 3. It should be applied so thoroughly as to cover the vulnerable 

 parts of the host plant with a uniform but thin and continuous layer. 4. Mix- 

 tures used on ripening fruit should not detract from its appearance and conse- 

 quent market value. 5. As a rule fungicides- should not be used when the plant 

 is in bloom. 



Bordeaux mixture, as already stated, has been found to be the most effective 

 general fungicide in use. Its value lies not alone in its immediate fungicidal 

 property but also in the fact that the copper salt which it contains is but slowly 

 soluble thus causing it to retain this property for a considerable period after it 

 is applied. The materials of which it is composed are cheap and readily obtain- 

 able and its preparation, while requiring care, should not be beyond the capa- 

 bilities of any fruit grower. 



While Bordeaux mixture is primarily a fungicide it has also been found to 

 possess some value as an insecticide. One of the desirable features of this mix- 

 ture is the fact that it may be combined with Paris green which is the most 

 common poison for combating leaf-eating insects. Thus two enemies may be 

 fought with one spraying mixture. (See Bui. No. 224.) 



