250 TWENTY-FIFTH ANNIVERSARY REPORT. 
over the sheet tents in that the cubic contents can be accurately 
computed once for all, thus avoiding the necessity of changing the 
amounts of the chemicals for each tree and thereby insuring correct 
treatment with the gas. Moreover the box fumigator does not rest 
on the trees and is not so apt to break the branches or brush off the 
buds or fruits. In the field tests with the box fumigators the Sta- 
tion concluded that the use of hydrocyanic acid gas in orchards in 
this State is only feasible on a few comparatively small trees which 
can be pruned back to 12 feet in height and 8 feet in diameter 
before adjusting the fumigator, and was impracticable for general 
orchard treatment. 
Experiments with kerosene-— With the entrance of this pest 
into the older orchards of New York, kerosene oil, pure or diluted 
to various strengths, was freely advocated for the treatment of the 
San José scale. As injuries had attended applications of the oil 
by fruit growers, it could not be recommended without knowing 
more definitely both the highest strength which could be used with- 
out injury to trees of different kinds and the lowest strength which 
would kill the scale under different conditions. Experiments! were 
conducted to determine the range of this oil for spraying purposes, 
and it was concluded that careful spraying of apples and pears 
at a strength of 4o per ct. in the spring as buds were swelling, was 
an efficient treatment for the San José scale. For spraying peaches 
and plums, oil treatment was considered inadvisable as they are 
very susceptible to injury. For these kinds of fruits, the safer 
sprays were recommended. 
Experiments with crude petroleum.— Following the demonstra- 
tion that kerosene oil under certain conditions could be used for 
the treatment of fruit trees, attention’* was then given to crude 
petroleum. Much interest had been aroused among orchardists as 
to the probable utility of this oil for this purpose because of some 
experiments conducted in other States south of New York, which 
showed that applications of undiluted crude petroleum, testing about 
45° Beaumé oil test, did not injure ordinary fruit trees when 
sprayed upon them, while an emulsion containing as little as 20 per 
ct. of oil seemed effective in destroying the scales. These effects 
upon the trees by the crude petroleum were contradictory to some 
*Buls. 194 and 213; same in Rpts. 19 :317-331 (1900) and 21:258-280 
(1902). 
*Buls. 202 and 213; same in Rpts. 20:247-291 (1901) and 21:258-280 
(1902). 

