66 THE CROWN-GALL AND HAIRY-ROOT. OF THE APPLE TREE. 
grown under the personal supervision of the writer. Both the scions 
and the seedling roots were grown in Virginia. The reason the 
stock was obtained from Virginia is that certain writers have in- 
sisted that most of the crown-gall comes from the West, especially 
from Kansas. Scions were taken of the following varieties: Wealthy, 
Gano, and Northern Spy. Before cutting it up into pieces for the 
root grafts two-fifths of the stock, both scions and seedlings, were 
dipped and thoroughly washed in a 2 per cent solution of copper sul- 
phate in water. The grafts were made in the ordinary manner of 
making commercial whip grafts, except that care was used in fitting 
the scion and root pieces together. The results of the experiment 
are given in Table XLIV, in the appendix. 
The results show a considerable decrease of crown-gall and hairy- 
root (13.8 per cent) in the case of the trees grown from disinfected 
stock, but this is more than offset by the decreased stand, which was 
less than one-half of that of the untreated trees. It is quite probable 
that there was enough copper sulphate present to interfere with the 
formation of the union in the graft, and it may yet be found that the 
use of a more dilute solution will prove beneficial. The experiment 
at least paves the way for further experimentation along this line 
with less concentrated solutions. Many of the scion pieces treated 
in the experiment died, while the seedling roots lived, thus indicating 
an imperfect formation of callus in the union, probably due to the 
action of the poison. 
PACKING AND STORING ROOT GRAFTS. 
There can be no question but that the packing and storing of root 
grafts before planting are of vital mportance in the prevention of 
disease. Care should be taken to use fresh new packing for this 
purpose, avoiding the use of material or boxes which have been used 
for packing trees that may have been diseased. The time of forma- 
tion of callus in the root graft is the most critical in the growth of the 
tree, and for this reason the grafts should be cared for with the 
greatest solicitude. 
In order to prevent the excessive formation of callus, which pre- 
disposes the grafts to attacks of the disease, it will be necessary to 
follow one of two procedures. The best method is to pack the grafts 
in clean moist sand, and after a few days’ favorable growing tempera- 
ture store them in cold storage but slightly above freezing, keeping 
them there until planting time. Good results may be obtained by a 
second method, in which a cool cellar is used for the immediate storage 
of root grafts as fast asthey are made. This method answers well if 
the temperature of the cellar can be kept at about 40° to 45° F., so 
that callus will form very slowly and the growth of shoots and roots 
will be held back. 
186 
