Apr. a8, Z933 
Peach Rosette, an Infectious Mosaic 
315 
NATURAL TRANSMISSION OF ROSFTTF 
The development of rosette in trees, often at a considerable distance 
from any known source of infection, indicates that winged insects or 
birds may be associated with natural transmission of this disease. 
Various insects are found associated with rosetted trees, the most 
abundant being the black peach aphis, Anuraphis persicae niger Smith. 
Numerous tests have been made by removing insects, including several 
species of beetles and leafhoppers from various parts of rosetted trees, 
and caging them on healthy peach and plum trees. In no case has 
rosette developed. At various times throughout the growing season for 
the past two years, numerous black peach aphids have been transferred 
from rosetted peach and plum trees to healthy peach, plum, cherry, 
apricot, and wild plum trees growing in cages. The colonies of aphids 
increased rapidly in size showing that they were under favorable condi¬ 
tions. In no case did rosette develop as a result of these aphid transfers. 
These tests indicate that the causal entity of rosette is not readily trans¬ 
ferred by the types of insects which are known to carry mosaic virus of 
other plants. 
The miter is of the opinion that further study will disclose the fact 
that an animal, other than man, is responsible for the dissemination of 
the causal entity of rosette. Therefore observations along this line are 
being continued. 
SUMMARY 
The data obtained from the foregoing experiments verify the findings 
of Smith to the effect that rosette is readily transmitted from peach to 
peach by infected buds. 
Rosette has also been transmitted to two varieties of apricots, two 
varieties of cultivated plums, one wild plum, one cherry, and two varieties 
of almonds by means of infected buds. 
On some hosts rosette produces a mottling of the leaves similar to 
mosaics. 
The Marianna plum is immune to rosette. 
Limited, tests indicate that rosette is not soil-transmitted. 
Numerous attempts to transmit rosette by means of sap from diseased 
trees has proved unsuccessful. 
In a large number of transfers of various types of insects from rosetted 
trees to healthy susceptible hosts, not a single case of rosette was trans¬ 
mitted. 
