SPRAYING WITH ARSENICALS. 183 
three-fourths of the cherries liable to injury by the curculio can be saved by two or 
three applications of London purple in a water spray in the proportion of 1 ounce to 
10 gallons of water. (2) That a sufficiently large proportion of the plum crop can be 
saved by the same treatment to insure a good yield when a fair amount of the fruit 
isset. (3) That ifan interval of a month or more occurs between the last application 
and the ripening of the fruit no danger to health need be apprehended from its use. 
(4) That spraying with the arsenicals is cheaper and more practical than any other 
known method in preventing the injuries from this insect. 
During the season of 1890 spraying experiments on a commercial 
scale were carried out by Mr. Weed in an orchard of 900 five-year-old 
plum trees in the fruit belt along the lake shore in northern Ohio, 
and a comparison was made relative to the merits of spraying versus 
jarring. As a result of this test several plum orchards in northern 
Ohio were sprayed for the curculio during 1891 and the consensus 
of opinion of the growers was in favor of the practice. Tests were 
also made the same season by the horticulturist of the Ohio Station, 
Prof. W. J. Green, both on the station grounds and in Ontario County, 
Ohio. Paris green was used in combination with Bordeaux mixture. 
The results on sprayed trees showed that about 20 per cent were 
injured by the insect, whereas unsprayed trees had about 70 per cent 
of injured fruit. 
Prof. Herbert Osborn, at that time an agent of the Division of 
Entomology of this department, also carried out spraying experi- 
ments in the use of arsenicals against the curculio during the summer 
of 1888. The poison used was London purple, at the rate of one-half 
pound to 100 gallons of water, with the addition of a small amount of 
soapsuds. The first treatment was given June 1, when the fruit was 
the size of small peas and before any indications of injury by the 
insect were to be found. The results of counts of all fruit from sev- 
eral varieties treated, sprayed and unsprayed, gave for the sprayed 
trees 32.48 per cent stung and 5.71 per cent containing larve. The 
unsprayed trees gave 41.86 per cent stung and 10.39 per cent of the 
fruit infested. It was concluded that the proportion of fruit stung in 
the orchard was so small as to give no benefit from spraying. 
London purple was also tested during the season of 1888 on plums 
by Mr. G. C. Brackett, at Lawrence, Kans. Prof. Cook, in Bulletin 
39 of the Michigan Agricultural Experiment Station, issued in 1888, 
says: 
It will be remembered that I have used the London purple several years with quite 
indifferent success to keep out principally the curculio. The fact that some fruit 
growers reported excellent success with this remedy led me to conclude that possibly 
I had not been persistent and thorough enough in this warfare. The curculio com- 
mences to work anywhere on the plum, which has a smooth surface, while the codling 
moth lays its egg right in the cup or funnel-like calyx end of the apple. Thus the 
wind and rain would free the plum or cherry or general surface of the apple of the 
poison much more readily and quickly than they would the rough cavity end of the 
apple. Thus we can understand how, granting that the arsenites are alike effective 
