216 VEGETABLE GROWING PROJECTS 



Then fill the barrel with water. You now have 50 pounds of 

 copper sulphate in 50 gallons of water, and 50 pounds of 

 lime in 50 gallons of water. This will make 625 gallons 

 of Bordeaux mixture and is enough to spray six acres once. 

 The remainder of the operation is also quite simple. Place the 

 spray rig most conveniently for filling. Fill about one third full of 

 water and add (assuming that the tank holds 100 gallons) 8 gallons 

 from the lime barrel. Stir well. Then add more water until the 

 tank is about three quarters full, and add 8 gallons, well stirred, 

 from the copper sulphate barrel, and fill the rest of the way full 

 with water. The tank now contains. 100 gallons of Bordeaux mix- 

 ture of the standard 4-4-5 formula or 8-8-100, costing 80 cents. 

 The whole operation takes about 30 minutes. It makes 

 spraying a one-man job. There is no mixing and stirring to get 

 the material into the tank, and there is no clogging of nozzles. 

 Spraying with Bordeaux controls the foliage diseases known as 

 late blight and early blight. The Bordeaux mixture never burns 

 the foliage and is a splendid carrier of insecticides, such as Paris 

 green, the arsenicals, and nicotine. Many times spraying with 

 Bordeaux results in an increased crop even when diseases are not 

 present to any extent. 



Rolling of the leaves, a, curly appearance, deformation of the 

 leaves, or a dwarfed condition of the plant, are evidences of dis- 

 eases known as leaf-roll and mosaic. Such diseases are trans- 

 mitted from one generation to another by the tubers, and when 

 they make their appearance care must be taken in the selection 

 of seed tubers. 



The tubers are often disfigured by scab, which may be pre- 

 vented by treating the seed potatoes with a formaldehyde solution 

 (1 pint to 30 gallons of water) for an hour and a half. 



1. What is the function of foliage in growing a crop of potatoes? 



