344. REeporRT OF THE DEPARTMENT OF ENTOMOLOGY OF THE 
DIPPING OF NURSERY STOCK IN THE LIME- 
SULPHUR WASH.* 
P. J. PARROPT, H. E.HODGKISS 4np W: J> oCH Omi. 
SUMMARY. 
Dipping in the lime-sulphur wash is a method of treatment pro- 
posed for the disinfecting of nursery stock for such pests as the 
San José scale, woolly aphis and other destructive insects. Its 
utility for these purposes has not been thoroughly established, and 
more knowledge on the safeness and efficiency of this treatment 
has been desired. This bulletin is a contribution of additional data, 
which ‘are based on experiments to determine: (1) The effective- 
ness of the lime-sulphur wash as a dip on the San José scale, and 
(2) the effects of dipping in this mixture upon the health of nursery 
recs: 
Tests were made of the standard lime-sulphur wash at tempera- 
tures of 60°, 100°, 120°, and 212° F. For purposes of comparison, 
experiments were also made with kerosene emulsion, containing 10, 
I5, and 20 per ct. of oil; miscible oil diluted with 10, 15 and 20 
parts of water; and hydrocyanic acid gas at the rate of 0.3 gram 
of potassium cyanide per cubic foot. The stock used for these 
tests was 180 3-year old Bartlett pears and 970 3-year old Ben 
Davis apples, all of which were infested with the San José scale; 
and 300 Mann apples, 470 Bartlett pears, 300 Satsuma plums and 
300 Fitzgerald peaches, all of which were clean and healthy trees. 
Immersion in the lime-sulphur wash at temperatures ranging 
from 60° to 120° F. and for time periods varying from instantane- 
ous dipping to immersion for ten minutes gave uncertain results on 
the scales. When heated to 212° F. the wash killed the scales and 
caused severe injuries to buds and bark, which ruined the trees. 
The wetting of the roots of fruit trees by this wash was generally 
accompanied with injuries. These were especially severe with 
Fitzgerald peaches and Ben Davis apples, of which 95 per ct. and 
96 per ct., respectively, were killed. The treatment, by immersion 
of the tops of apples, pears, peaches and plums, for less than three 
minutes in the sulphur wash, at temperatures of 60° to 120° F., was 
usually unattended with appreciable injuries. 
* A reprint of Bulletin No. 302. 
