BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 21 
FRUIT AND NUT INSECTS 
Phony Peach Vectors Incriminated 
Climaxing 12 years' experimentation, definite evidence was ob- 
tained in 1948 that certain leafhoppers transmit the phony peach dis- 
ease. This virus disease has caused the loss of more than one million 
peach trees since 1929. Inspection of peach trees exposed to infection 
in insect-transmission tests begun in 1945 and 1946 resulted in the 
finding of 14 definite and 10 probable cases of phony peach. Four 
species of leafhoppers — Homalodisca triquetra (F.), Graphocephala 
versuta (Say), Oncometopia undata (F.), and Cuerna costalis (F.) — 
were definitely incriminated as capable of transmitting phony peach. 
All four of these leafhoppers are general feeders, and the first three 
are known to be associated with peach trees at certain seasons. C. 
costalis, although not commonly found on peach trees, has survived 
for a month or more when confined on peach. It is possible that other 
species, particularly members of the Tettigellinae, the group to which 
all the incriminated leafhoppers belong, may also spread the disease. 
Several other species of this group are of common occurrence in the 
area in which phony disease spreads rapidly. This work has been done 
in cooperation with the Bureau of Plant Industry, Soils, and Agri- 
cultural Engineering. 
Discovery of insect vectors of phony peach disease opens up a new 
avenue of approach in the development of methods of restricting 
or preventing its spread. A large-scale experiment aimed at control 
of the vectors has already been undertaken in Georgia, where DDT has 
been applied to more than 90,000 peach trees. Because of the long 
incubation period of the virus causing the phony disease, at least two 
growing seasons, the results will not be measurable until 1951. This 
large-scale experiment supplements a number of large block tests 
with DDT that were started in 1947, when the identity of the vectors 
was already suspected. 
Tests of New Insecticides Against Fruit and Nut Insects Continued 
The practical development of promising new insecticides and the 
preliminary evaluation of other newly available materials constituted 
a major portion of the work on pests of fruits and nuts. The more 
important results of this work are reported in the following para- 
graphs, except those with parathion for scale-insect control, which are 
presented in a separate section. These results should not be considered 
as recommendations for the general use of these materials. 
Apple insects 
In codling moth control DDT continued to give outstanding results- 
and was superior to all other materials tested. From 1 to 2 pounds of 
a 50-percent wettable powder in 100 gallons was used in three to six 
cover sprays, depending on the region. In Indiana a 25-percent para- 
thion wettable powder was about as effective, pound for pound, as 
50-percent DDT when the spray interval did not exceed 1 month. Five 
applications of a spray containing 10 ounces of such a powder in 100 
