66 FUNGOUS DISEASES AND SPRAYING 



trees should be disinfected by a thorough spraying with 

 Bordeaux mixture before the buds open ; a second spraying 

 should be given just after the fruit has set. As ripening 

 approaches the spraying should be repeated at intervals of a 

 week or ten days, using the solution of copper carbonate 

 instead of Bordeaux to avoid staining the fruit. The rotting 

 plums should be thoroughly gathered and burned. 



The above spraying will also be useful in checking the black 

 knot and the disease known as '•'' shot liole .'' This is a 

 disease in which the fungus kills a small circular area of the 

 leaf, which later drops out leaving a " shot hole ." 



The cherry is attacked also bv these diseases and may be 

 treated in the same way. 



POTATO 



Early Blight. Dark brown or black spots with sharp mar- 

 gins upon the leaves, increasing in size and number, finally 

 killing the vines ; usually appears on late potatoes the latter 

 part of July. 



Late Blight and Rot. Rapidly progressive wilting and dy- 

 ing of the leaves, a whitish mold-like growth appearing on the 

 under side ; accompanied by rotting of the tubers ; appears in 

 August. 



These two diseases are frequently present together. 



Treatment. Spray with Bordeaux mixture by the middle of 

 July, a second time the first of August, a third time the middle 

 of August. When bugs are present at either of these spray- 

 ings they may be killed by adding half a pound of paris green 

 to a barrel of the Bordeaux. 



There is no question of the profit of spraying potatoes in 

 regions where these blights are prevalent. The cost of spray- 

 ing an acre three times as above will vary from $6.00 to 

 $9.00; a saving of twice that number of bushels will usually 

 pay the cost. The following is the summary of nine experi- 

 ments : Smallest number of bushels per acre saved by spraying 

 21, largest 82, average 49. Supposing the cost of spraying 

 in each case to have been $9.00 per acre and the value of the 

 potatoes to have been 50 cents per bushel : The profit would 

 have ranged from $1.50 to $32.00 per acre, the average being 



