214 



Minnesota Plant Diseases. 



are eaten by man or used in the manufacture of wine. In the 

 first place spraying at the time of maturity of the fruit is seldom 

 if ever necessary. In the case of earlier sprays it has been shown 

 that no danger exists to man from the eating of such fruits. 

 It has been estimated that of grapes sprayed with bordeaux in 

 the usual way an adult may eat "three hundred to five hundred 

 pounds per day without ill effects of copper." Even in the case 



FIG. 105. A simple type of barrel pump used in the horticultural department of the 

 Minnesota Agricultural Experiment Station. A return pipe keeps the liquid in the 

 barrel stirred up. The fluids are strained through the brass strainer shown above 

 when poured into the barrel. Photograph by R. S. Macintosh. 



of arsenic treatment of apples for insects it has been shown that 

 "even though all of the poison sprayed upon the apples in 

 making necessary treatments should remain there undisturbed a 

 person would be obliged to eat at one meal eight to ten bar- 

 rels of the fruit in order to consume enough arsenic to cause 

 any injury." Fruits should not, however, be sprayed with ar- 

 senic within two weeks of picking. In the case of the use of 

 corrosive sublimate for seed potatoes, however, the potatoes so 



