New YorK AGRICULTURAL EXPERIMENT STATION. 279 
ity of 0.79 (4814° to 44° on Baumé oil scale) providing the appli- 
cations are made after the buds commence to swell. While if 
treated when dormant the trees are generally injured and in 
many cases killed outright. 
As a whole, the results of tests on apple and pear are still 
more confusing. Our tests show plainly that pears can not be 
treated after buds have commenced to swell; they also indicate 
that the same is true of apples. The majority of results indicate 
that apple can be treated while perfectly dormant with little 
danger of injury even with 50 per ct. mechanical mixtures of 
crude petroleum.4 
Effect on scale—— The results indicate first, that one applica- 
tion of a 15 per ct. mechanical mixture of crude petroleum, 
specific gravity 0.79, did not kill all the scale insects, even 
though they were situated in exposed places. 
Second, that double applications of the above percentage of 
crude petroleum killed all that were reached as did also all the 
25 per ct. mechanical mixtures whether double or single applica- 
tions.- - 
In addition the results show, that it is a mechanical impossi- 
bility to reach those individual scale insects protected by buds 
or rosettes of buds with crude petroleum, without drenching the 
buds to such an extent as to injure the latter. 
COST OF SPRAYING. 
Smith has stated that the cost of spraying with kerosene or 
with crude petroleum need not exceed one or two cents per tree, 
meaning of course very small trees. 
It cost us seven cents per tree for crude petroleum to spray 
pear trees averaging 12 feet high, and 5 cents per tree for labor, 
making a total of 12 cents per tree. 
The cost of crude petroleum for spraying standard apple trees 
averaging 25 feet high, was 30 cents per tree, estimated cost 
of labor per tree, 10 cents, making a total of 40 cents per tree. 
As set forth by Dr. Smith there is no insecticidal value in the water used. The latter 
aimply acts as a carrier, helps to avoid drenching and at the same time lessens the expense. 
On small trees and shrubbery which can be painted by hand or sprayed with an atomizer, 
water is a detriment. : : 
