474 
that all roots and stumps be carefully re- 
moved from the earth in clearing, and 
that before planting trees, the soil be de- 
voted to other than orchard crops for 
several years until the root-rotting fungus 
has had a chance to die out. 
Evidence that much of the infection 
takes place where trees are injured by 
cultivation leads to the suggestion that 
cultivation close to the tree be done with 
greatest care to avoid injury. At the 
same time thorough cultivation has been 
advised in order to establish good aera- 
tion of the soil, since this condition is 
supposed by some to be unfavorable to 
the progress of the disease while it un- 
doubtedly promotes the vigor of the tree. 
When trees are once attacked by the 
fungus, death, almost without exception, 
is only a question of time. It seams use- 
less, therefore, to retain in the orchard 
trees which will be worthless to the own- 
er and which may become a source of in- 
fection for other trees. It has conse- 
quently been considered best to grub up 
at once any tree discovered to be diseased 
and to remove it from the orchard, taking 
out at the same time as much of the root 
system as possible. It has also been ad- 
vised not to plant another tree in its 
place for at least three years. 
If it should seem desirable to retain 
temporarily a tree known to be diseased, 
it would perhaps be safest to dig a trench 
about two feet deep around the tree near 
the tips of the roots in order to prevent 
the rhizomorphs, which rarely occur 
deeper than this, from spreading to other 
trees. Throw the dirt inside the ditch. 
Where conditions are such that the dis- 
ease appears to be spreading rapidly from 
tree to tree, the heroic method of uproot- 
ing healthy trees in advance of the zone 
of infection has been suggested; but as 
far as we know, the disease rarely as- 
Sumes such a condition in the Northwest 
as to warrant so drastic a method of 
treatment. 
On account of the possibility of infec- 
tion from spores produced by the mush- 
rooms, all fruiting bodies appearing at 
the base of diseased or dead trees, or in 
other places in the orchards and fields, 
ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
should be collected while still in the but 
ton stage and destroyed by burning 
Knocking them over does not prevent 
spore formation. 
The effect upon the disease of various 
chemical substances worked into the soi] 
around a tree has never been thoroughly 
tested out. This line of investigation may 
prove to be worth while, and growers are 
urged to make experiments upon trees 
known to be affected. A record of the 
exact treatment should be made and notes 
kept regarding the effect in each case 
Those who possess sufficient patience 
and skill, and are willing to devote the 
necessary time, may be able by the fol- 
lowing method to save individual trees 
that are not too far gone when the dis- 
ease is discovered. This method has been 
used in one Oregon apple orchard with 
considerable success. "Whether it can be 
applied as well to other kinds of fruit 
trees remains to be seen. At the first 
sign of unhealthy foliage the tree is ex- 
amined for root rot. Where this is found, 
the earth is removed from the base of the 
tree and the main roots are exposed for a 
foot or more. The soil is also removed 
from beneath the roots. The air and sun- 
shine have access in this way to the 
crown and root bases. The dead portions 
of the bark are carefully and completely 
removed from trunk and roots. If a root 
is girdled, it is taken out entirely. After 
all the diseased parts of the tree are cut 
out, the exposed surfaces are washed with 
some disinfectant, such as Bordeaux mix- 
ture or corrosive sublimate. When they 
are dry, walnut grafting wax is applied. 
Then, in order to restore as quickly as 
possible the area of the trunk destroyed 
by the fungus, bridge-grafting is resorted 
to. A number of scions are inserted into 
the healthy tissue of the trunk just above 
the dead part, and their lower ends are 
connected with healthy roots. This is a 
delicate operation and the trees have to 
be braced to prevent the scions from pull- 
ing out. In an orchard recently visited 
by the writer, a few young bearing apple 
trees which were treated in this way two 
years ago are now apparently free from 
any trace of disease and as thrifty as any 
