204 THE PLUM CURCULIO. 
arsenate largely defoliated the trees and burned the fruit. There 
was, however, little foliage injury from the commercial arsenate of 
lead, though the fruit was injured and nearly all fell from the trees 
before ripening. In Georgia both forms of arsenate of lead defoliated 
the trees almost completely and injured the fruit to a serious extent, 
the homemade lead arsenate being the more injurious. 
Also, during 1906, in Virginia, several other commercial brands of 
arsenate of lead were tried and no difference between them could be 
distinguished as to their effect on foliage and fruit. Arsenic sulphid 
in paste form, at the rate of 2 pounds to 50 gallons of lime water, was 
applied once and quickly defoliated the trees, killing the twigs and 
smaller branches, resulting finally in the death of several of the trees 
sprayed. During 1907 eight additional brands of arsenate of lead 
were tried in Virginia with from 1 to 4 applications in strength, 
varying from 1 to 3 pounds per 50 gallons of water. These were 
used with and without lime. Two applications at the rate of 2 
pounds to 50 gallons of water, plus 2 or 3 pounds of stone lime, were 
found reasonably safe; and this treatment was adopted for recom- 
mendation to growers, although the risk of possible injury was 
pointed out. 
In cooperation with the Bureau of Chemistry an inquiry was 
started in 1907 to determine if possible the reasons for injury to 
peach foliage from arsenate-of-lead sprays. The results of the work 
during 1907 and 1908 have been stated by Messrs. J. K. Haywood 
and C. C. McDonnell,! and conclusions were presented from the ex- 
periments in 1909. These studies have been extensive and are 
interesting as bearing on the causes of the decomposition of lead 
arsenate when sprayed on peach trees, resulting in injury to foliage 
and fruit. The idea of decomposition of the poison by the action 
of the carbon dioxid of the air was disproved by numerous tests, 
but it was found, in an examination of water used in spraying, that 
this contained a sufficient quantity of sodium chlorid (common salt) 
to decompose an appreciable quantity of the lead arsenate; and it 
was concluded that if certain salts commonly present in water were 
present in more than very small quantities they would exert a solvent 
action on the arsenate of lead. Concerning this matter Messrs. 
Haywood and McDonnell state. 
(1) When applied with spring water (analysis of which has been given), some injury 
to foliage resulted, but it was not nearly so marked as in the preceding year, and a 
longer time elapsed before the injury was noticeable. 
(2) When applied with distilled water very slight injury occurred, noticeably less 
than when the spring water was used. 
(3) When applied with distilled water to which 10 grains per gallon of sodium 
chlorid had been added, rather serious injury resulted. Whei distilled water con- 
1 Bul. 131, Bur. Chem., U. S. Dept. Agr., p. 49, 1910, 
