3 o8 
Journal of Agricultural Research 
Vol. XXIV. No. 4 
PEACH TO PEACH, PLUM, AND APRICOT 
Experiment i. —In the spring of 1919, rosette appeared on one side 
of a six-year-old seedling peach tree in an experimental orchard at the 
station. The other side of this tree appeared normal throughout the 
summer of 1919. During this time buds from healthy peach, plum, and 
apricot trees were inserted into the new growth of the normal appearing 
branches. The plum buds failed to unite with the peach stock. The 
peach and apricot buds united with the peach stock, but remained 
dormant throughout the summer. In the spring of 1920, the branches 
of the seedling peach which showed rosette in 1919, did not produce 
leaves, and examination showed that they were dead. The branches 
which appeared normal in 1919 produced rosetted growth in the spring 
of 1920. The peach and apricot buds inserted in 1919 produced typical 
rosetted shoots showing that the causal entity had passed from the 
diseased peach stock to the buds. The apricot buds produced shoots 
from two to three inches in length and the leaves had the mottled appear¬ 
ance of a mosaic disease. The mottled appearance was not so striking 
on the peach leaves. The shortened internodal growth, together with 
mottling of the leaves of some hosts and the absence of microscpic 
bacteria, put peach rosette in the class of virus or mosaic diseases. This 
experiment indicated that both the peach and the apricot are hosts for 
rosette. 
PEACH TO PEACH 
Experiment 2.—On June 10, 1919, buds from a healthy Elberta 
peach tree about 20 years of age were put in the new growlJi of two 
seedling peach trees about two years of age to serve as controls. Oh 
the same date buds from rosetted shoots of the seedling peach described 
in experiment i were put in the new growth of two pea^ seedlings the 
same age as the controls. On August 29, 1919, it was observed that 
the Ell^rta buds on the control trees had grown into healthy shoots. 
In one of the inoculated trees a diseased bud had developed a ; rpsette 
of leaves, and below the point where this bud was inserted some of the 
buds of the stock had developed rosettes characteristic of; thus disease. 
In the other inoculated peach seedling the bud had remained dormant, 
but the buds of the stock immediately below the point of inpcuiation 
had developed typical rosettes. In May, 1920, it was observed that the 
two control trees were Healthy and growing Tdgorously, while the in¬ 
oculated trees had become completely rosetted (PI. i, A). 
PEACH TO APRICOT TO PEACH 
Experiment 3.—On August 15, 1919, two buds from a rosetted twig 
of the peach tree described in experiment i were put into the new growth 
of a healthy Royal apricot, which was in its second year of growth. 
The peach buds remained dormant until the spring of 1920 when they 
developed into rosetted shoots. The lateral buds on the apricot branch 
below the point of inoculation also developed weak shoots, but the 
leaves did not have the typical rosetted appearance. The internodal 
growth, although longer than that of the rosetted peach shoot (PI. 2, A), 
was much less than that of healthy apricot trees growing near. Plate 
2, B, shows the stunted growth of this Royal apricot 12 monflis after inocu¬ 
lation with peach rosette. While the growth is not t3p)ical of rosette as 
