BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 57 
infection on healthy elms. Mist blowers, hydraulic sprayers, and a 
helicopter were used in other areas to test methods and DDT formu- 
lations. Twig samples taken from these sprayed elms were exposed 
to bark beetles, and examined to determine the adequacy of initial 
deposits and residual DDT for preventing- bark beetle feeding. 
Quantitative analyses of the DDT were made on the same samples. An 
early-spring application, with a hydraulic sprayer, of a 2-percent 
DDT emulsion followed by a 1-percent DDT emulsion gave con- 
sistently good results. 
Continued attention was given to possible injury to elms and other 
trees, to turf grasses, and to birds, fish, and other animals caused by 
the application of large amounts of DDT and its solvents. Spider 
mites became abundant on the sprayed elms in the large test plot, 
apparently as a result of the spraying, and steps were taken to con- 
trol this secondary pest. 
Inspection for Peach Diseases Protects Industry 
Inspection of nurseries to prevent spread of the phony peach and 
peach mosaic diseases was continued during 1949 in cooperation with 
State agencies. 
In 14 States 2,300,000 trees in 239 nurseries and 415,000 orchard trees 
within a 1-mile radius of these nurseries were examined, as well as 35 
budwood sources with their 1-mile surroundings comprising 56,800 
trees. Be}^ond regulated areas an additional 188 nurseries producing 
7,936,000 nursery stock trees and the 239,300 orchard trees in their 
environs were examined as a precautionary measure. 
In the peach mosaic area State certification was withheld from 35 
nurseries — from 2 because of disease on the nursery premises and from 
33 small nurseries because diseased trees remained on the property 
after May 15. Four budwood sources were refused certification be- 
cause of local mosaic conditions. In the phony peach area one nursery 
failed to qualify. 
During the calendar year 1948 nearly 40,000 orchards containing 
nearly 9,000,000 trees were examined in 186 counties in 15 States. 
Approximately 68,500 diseased trees were found in these orchards, and 
more than 90 percent of them were promptly removed. 
This program, begun in 1936, has prevented spread of these diseases 
through nursery-stock channels. It has lowered the general orchard 
incidence of peach mosaic from 45,063 infected trees recorded in 1936 
to only 7,447 trees in 1948. The work has also greatly reduced the 
phony disease as a serious orchard problem in all but two States, Ala- 
bama and Georgia, where special conditions appear to favor this 
infection. 
Resurvey Fails To Reveal Citrus Canker in Texas 
Reinspection of all citrus trees in Texas on or near properties upon 
which citrus canker has been found since 1920 and the examination of 
Poncirus trifoUata hedges throughout eastern Texas were continued 
through April 1949. Since this resurvey was begun in September 
1947, crews have examined over 4,000,000 citrus trees, escaped plants. 
