BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 21 
knowB healthy but susceptible - with % a view to determining 
whether the grafted trees mighi be symptomless carriers. The prac- 
ticability of this method of inspection will not be determined until the 
present crop seas< n is over. 
During the year 147 Bureau and 69 State inspectors were employed 
on the project, in addition to an average of nearly 650 relief workers. 
After the 1939 inspection season the States of Alary land and Okla- 
homa were released from the area quarantined on account of phony 
peach disease, since no diseased trees were found by inspection during 
a period of 3 years of properties previously known to have been in- 
fected, and contiguous properties. Many counties in other States were 
also eligible for removal from quarantine. However, no action was 
taken by the States to remove these counties from quarantine, since all 
nurseries therein could comply with the quarantine-certification 
requirements. 
CITRUS CANKER ERADICATION 
Repeated and thorough inspection work was conducted in areas in 
Louisiana and Texas in which citrus canker had been found since the 
intensive survey of 1935, and the program was extended to include a 
number of additional counties. One recurring infection and one in- 
fection on a property in which disease had not previously been detected 
were found in Brazoria County, Tex. The 106 infected trees in these 
areas consisted of small seedlings, which in the case of the property 
not previously known to be infected had been cut off by a mowing 
machine. The discovery of infection under such circumstances is 
indicative of the thorough and intensive nature of the inspection 
program. 
The employment of relief labor from allotments from emergency- 
relief appropriations made possible the removal and destruction of 
over 2,000,000 escaped and abandoned citrus trees, a large majority 
of which were Citrus trifoliata seedlings. This type of work is a very 
essential part of the eradication program, since it results in elimination 
of escaped and abandoned trees that might harbor the disease. 
INSECTS AFFECTING FOREST AND SHADE TREES 
PROGRESS MADE IN THE CONTROL OF BARK BEETLES 
WESTERN PINE BEETLE 
Recent studies in the commercial pine forests of California and 
Oregon have emphasized the development of methods of classifying 
forest stands as to their relative susceptibility to attack by bark beetles. 
It is believed that the danger of serious outbreaks may be greatly re- 
duced by making forest stands more resistant to attack through -elec- 
tive cutting of high-risk trees and by giving priority in logging pro- 
grams to areas of greatest beetle hazard. Large tracts of forest land 
have been surveyed and zoned as to relative degree of hazard, and it is 
planned to complete this work over practically all the commercial pine 
area. This information is of direct value to the Forest Service, the 
Office of Indian Affairs, and those owning huge tracts of timber in 
planning their sales and cutting programs. 
Much of the high-quality lumber m the commercial pine stands of 
northeastern California is contained in overmature trees, in vurying 
