New York AGRICULTURAL EXPERIMENT STATION. 
As the scale is distributed locally by such agencies as insects, 
birds and the wind a careful watch should be kept in the orchard 
for its appearance. Orchard trees that have become infested if 
considered too valuable to destroy may be treated either by 
applying a wash or by fumigation with hydrocyanic acid gas. 
The former method is the only one practical for large trees, such 
as full-grown apples, and may be employed for smaller trees as 
well. Crude petroleum is one of the best washes that has been 
extensively used in the East, although as noted on a subsequent 
page, a number of others have recently given promising results. 
Crude petroleum may be used upon apple, pear and cherry trees, 
in an emulsion with water, in the proportion (40 per ct. of petro- 
leum) required to kill the scale, without danger of serious injury 
provided the application is made in early spring. Plums may 
also be treated with the petroleum-water emulsion but there is 
more danger of injury. Peaches should not be treated with the 
emulsion stronger than 25 per ct. petroleum. For summer treat- 
ment a 25 per ct. emulsion may be used, with reasonable cer- 
tainty of killing the scales that are reached by the spray. When 
purchasing crude petroleum it should be remembered that it is 
safer to use an oil having a specific gravity of 43° than lower. 
The principal advantage of fumigation over treatment with 
any of the washes is the thoroughness with which the gas does 
the work. If properly done, probably every scale will be killed 
by fumigation while it is very difficult, if not impossible, to hit 
ail of them with a spray. The use of the gas in the orchard is 
practically limited, however, to comparatively small trees be- 
cause of the expense and difficulty of fumigating large ones. 
Trees that can be cut back to about twelve or fourteen feet in 
height by eight or nine feet in diameter can be easily and cheaply 
fumigated. 
