348 Report oF THE DEPARTMENT OF ENTOMOLOGY OF THE 
EXPERIMENTS IN DIPPING MADE AT THIS STATION. 
OBJECTS. 
The experiments reported in this bulletin were undertaken for 
the purpose of contributing further data on the value of dipping 
in the lime-sulphur wash for the treatment of nursery stock infested 
with the San José scale. The principal factors to be considered in 
determining the utility of the mixture for this purpose are its 
efficiency and safeness. In this inquiry, efforts were largely di- 
rected toward ascertaining: (1) The effects of the treatment on 
the scale, and (2) the effects of the treatment on the trees. 
The ultimate aim of this work is to determine the value of the 
more efficient spraying mixtures for the disinfection of nursery 
trees for the common injurious insects. This information is 
especially sought for by fruit-growers, who are gradually realizing 
the desirability of treating their own purchases of stock before 
planting, for woolly aphis, peach aphis, San José scale, etc. A safe 
and efficient dip for these purposes would encourage the fruit- 
grower to rely more on his own efforts to protect the trees and less 
on the nurserymen, and would aid in dispelling the present uncer- 
tainty and confusion that now attends the placing and filling of 
orders for nursery stock. 
OUTLINE OF THE EXPERIMENTS. 
For the experiments 970 Ben Davis apples, 300 Mann apples, 650 
Bartlett pears, 300 Satsuma plums and 300 Fitzgerald peaches were 
used. The trees were three years old. The Ben Davis and Bart 
lett stocks were generally well infested with the scale while the 
remainder of the trees were clean. The standard lime-sulphur 
wash was used for the larger number of the experiments, but com- 
parative tests were also made with kerosene emulsion, containing 
IO, 15 and 20 per ct. of oil, with miscible oil diluted with 10, 15 and 
20 parts of water, and with fumigation, using potassium cyanide at 
the rate of 0.3 gram per cubic foot. In the dipping operations the 
trees were immersed singly. For the main portion of the experi- 
ments, the temperature of the spraying mixtures was 60° F. To 
determine the effects of higher degrees of heat and prolonged im- 
mersion on both scales and trees, tests were made with these mix- 
tures at temperatures varying from 60° to 212° F., and with time 
periods varying from instantaneous dipping to immersion for ten 
minutes. To ascertain the effect upon the health of the plants of 
wetting roots with the sprays, in most cases half the trees in each 
