New YorK AGRICULTURAL EXPERIMENT STATION. 259 
It is unsafe to treat pear and probably apple with crude 
petroleum of the strength given, after buds have commenced 
to swell; but even 50 per ct. mechanical mixtures may be used 
on dormant apple and pear trees. Scale insects, even when 
fully exposed, were not all killed by a 15 per ct. strength of 
crude petroleum; though two applications of this strength were 
effective or one of the 25 per ct. strength. 
INTRODUCTION, 
As stated in Bulletin No. 209, conflicting results have been 
obtained from the various methods of combating the San José 
scale-insect. Consequently, it is a difficult matter to recommend 
any method and not have the recommendation opposed by nega- 
tive results obtained in some cther section of the country. For 
the most part, the conflicting results have been obtained in the 
use of coal-oil in some of its forms; although some such results 
have been secured when different experimenters have used the 
so-called “ whale-oil soaps.” In the latter case the diversity of 
results is probably due to the use of a soft soap in one case and a 
hard soap in another. 
The tests given in the following report indicate that the diverse 
results obtained in using kerosene and crude petroleum by dif- 
ferent testers can be accounted for by the lack of uniformity in 
time of making tests, in variety of trees treated, in grades of oil 
used, or in methods of application. 
HISTORY OF STATION TESTS. 
In Bulletin No. 194 of this Station results are given of careful 
tests in western New York, on dormant trees under nursery con- 
ditions, with two grades of kerosene, each undiluted and com- 
bined with different percentages of water; and in Bulletin No. 
202, tests with crude petroleum in the same section are described. 
The experiments here reported were made in southeastern 
New York at the same time as those noted in the bulletins just 
referred to. The same grades of kerosene and their mechanical 
mixtures were used on dormant trees under orchard conditions 
on Long Island; and, later, tests were also made with two grades 
of crude petroleum. 
