2 BULLETIX 1027, V. S. DEPARTMENT OF AGEICULTUEE. 



ravages of the Colorado potato beetle. In 1872 Le Baron (70) sug- 

 gested the application of Paris green to fruit trees to combat the 

 spring cankerworm, but Lodeman (75) states that only a few of the 

 most progressive orchardists adopted arsenical spraying against 

 the codling moth until after the establishment of the State agri- 

 cultural experiment stations resulting from the passage of the Hatch 

 Act in 1887. 



The question soon arose as to the possible danger to the consumer 

 from the use of potatoes the vines of which had been treated with 

 a poisonous compound, such as Paris green. One of the first in- 

 vestigators of this subject, Kedzie, in 1872 (64) and 1875 (65), con- 

 cluded "that there is but very little danger of the potato tuber 

 being poisoned so as to endanger the health of the consumer. Ar- 

 senic is equalh' deleterious to the vegetable as well as the animal 

 system. If added in dangerous quantity to the plant, the plant 

 dies, no potatoes are formed.'' McMurtrie (78) detected no arsenic 

 in potatoes which had been subjected to applications of Paris green. 



Lodeman (75) states that London purple was recommended as 

 an insecticide in 1877. Cook (26), who sprayed apple trees on 

 May 25 and June 20, 1880, at the rate of 1 pound of London purple 

 to 100 gallons of water, reported that 100 blossom ends cut from the 

 sprayed trees on August 19 showed no trace of arsenic. He proved 

 also (27) that it took but a very small amount of the arsenites to 

 kill potato beetles, currant slugs, and cabbage caterpillars, and 

 discovered that the poison was retained on plants sheltered from 

 rain for 10 to 20 days. He concluded that it was safe to use Paris 

 green or London purple on trees the fruit from which would not be 

 eaten for four or five weeks after the application. 



Wheeler (132) , in 1888, reported that it was safe in California, where 

 rainless summers prevail, to spray vines with Paris green. When the 

 vines were sprayed with 1 pound of Paris green to 16 gallons of water, 

 "ten times as strong as the solution recommended for general use," 

 Rising (114), the State analyst, found only traces of arsenic on the 

 grapes and none in the wine made therefrom. 



Objection was offered to the use of arsenicals, on the ground that 

 they frequently caused more or less injury to the foliage. Gillette 

 (58), however, found that "lime added to London purple or Paris 

 green in water greatly lessens the injury that these poisons would 

 otherwise do to foliage." Weed (129) recommended applying 

 insecticides and fungicides together, and Gillette (58) showed that 

 London purple can be used at least eight or ten times as strong 

 without injury to foliage if applied in common Bordeaux mixture 

 instead of in water. Gillette (59) stated, in 1891, that a mixture of 1 

 ounce of Paris green to 100 ounces of flour was the most effectual 



