BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 75 
2.5 percent of those inspected. Mosaic infection was discovered in 
5,400 trees, or 0.2 percent of the inspected trees. 
After 2 years of area-wide inspection and removal of infested trees 
in Georgia, the incidence of phony peach disease dropped from 6.05 
percent in 1951 to 4.77 percent in 1952. In the Fort Valley area, the 
most severely infected commercial growing area, the reduction was 
from 8 percent in 1951 to 6.3 percent in 1952. 
Within the peach mosaic control area, there was a reduction in 
disease prevalence in 1952 in the States of Arkansas, California, and 
Utah. No change was observed in Texas, and Colorado infections 
showed an increase fiom 0.22 to 0.32 percent. 
The 1952 inspections showed Comanche, Henderson, Mills, Parker, 
and Wilbarger Counties, Tex., to be mosaic-free for the third consecu- 
tive year. They are therefore eligible for release from the State's 
standard peach mosaic quarantine. 
Four nurseries growing 17,101 trees in the peach mosaic regulated 
area failed to comply with certification requirements. Two nurseries 
with a total of 385 trees were found to be ineligible for certification 
under the Standard State Phony Peach Quarantine. A total of 141 
nurseries propagating 870,000 peach trees, and their environs, were 
inspected. These nurseries were located in 25 regulated counties of 
8 States. 
Precautionary inspections were made in commercial peach nursery- 
stock-producing areas outside those now regulated under State phony 
peach or peach mosaic quarantines. These inspections included 35 
nurseries propagating more than iy 2 million trees. Approximately 
34,000 trees were inspected without finding any evidence of either 
disease. 
Twenty-three peach budwood sources and their 1-mile environs in 
the peach mosaic-control area were inspected and certified. These 
sources, totaling 79,000 trees, are located in Arkansas, California, 
Colorado, Oklahoma, and Texas. Three mosaic-infected trees were 
found and removed on properties adjacent to these certified budwood 
sources. Budwood from certified sources is cut under the supervision 
of an inspector, who also reinspects trees in the peach mosaic-regulated 
area before the buds are cut. Budwood sources outside the peach 
mosaic-infected area were inspected with negative results in 13 coun- 
ties of 5 States. 
Insect Vectors Are Lifetime Carriers of Phony Peach Disease Virus 
Phony peach transmission tests in 1952 indicate that insect vectors 
of this disease when once infected can infect new trees during the 
remainder of their lives. This is so even though they feed intermit- 
tently for considerable periods on plants not susceptible to the disease. 
The most favorable period for experimental transmission has been 
found to be from early April until the middle of July. 
Economic Damage by Phony Peach Disease Traced to Single Vector 
Although four kinds of leaf hoppers have been found capable of 
transmitting the phony peach disease, serious economic damage does 
not occur except in areas where Homalodisca triquetra, the most im- 
portant vector of the disease, occurs. This has been demonstrated in 
