EXPERIMENT STATION BULLETINS. 371 



MINEEAL EE8IDUES IN SPRAYED FRUIT. 



Part of Bulletin No. 101. — Chemical Department. 



The practice of spraying fruits with certain mineral compounds to destroy 

 insects and fungi has called out discussion in regard to the ripened fruit 

 after such spraying, and its fitness for food. The subject has awakened an 

 earnest discussion and many wild statements have been made on both sides 

 of the subject. The first condition for intelligent discussion of any sub- 

 ject is to know the facts in the case. 



The Horticultural department in 1892, and again in 1893, sent to the 

 Chemical department specimens of fruit for analysis which had been 

 sprayed during the season of growth, with a careful statement of the com- 

 position of the mixture used in spraying, the quantity used, and the dates 

 of application. 



Two kinds of spraying mixtures were used. No. 1 consisted of 1 Bb Lon- 

 don purple in 200 gallons of water; and 6 lbs of CUSO4, SHgO (crystallized 

 sulphate of copper) and 41bs of lime in 32 gallons of water, the spraying 

 mixture (unless otherwise stated) consisting of equal measures of the Lon- 

 don purple and the Bordeaux compound. The No. 2 spraying mixture 

 differed only in the use of 2 Bbs of the copper salt and If lbs of lime for 32 

 gallons of water with an equal measure of the London purple mixture. 



In stating the results of analysis the calculation is made on the basis of 

 one pound avoirdupois of fruit, and the metals found in a pound stated 

 in grains; the "arsenic" as white arsenic (AsoOj) and the "copper salt" 

 as blue vitriol (CuSO^, SH^O). 



RESULTS IN 1892. 



Strawberries No. 1. Sprayed with No. 1 mixture June 18 and 23, one 

 half gallon on one rod of row. Picked June 24. Fruit excessively sprayed, 

 the berries nearly covered with the mixture. 



Arsenic found .044 grains 



Copper salt 4.87 



Strawberries No. 2. Sprayed June 18 and 23 with No. 2 mixture, one- 

 half gallon to rod of row. Picked June 24. Excessively sprayed. 



Arsenic found .0298 grains 



Copper salt 1.821 



