Oxford Democrat. [volume] (Paris, Me.) 1833-1933, 1908-03-17
Black Knot on Plum Trees.


Some weeks ago President Craig of
the Maine State Pathological Society
favored the Farmer with some of his
experience in plum growing and our
readers will be interested in the follow
ing supplementary points from him on
handling and control OF this dreaded
hindrance to plum culture. Mr.. Craig
says:
In my article on Successful Plum
Orchard" the danger of harboring
Black Knot was briefly touched on, and
as find many are anxious TO eradicate
this very destructive disease, thought
it advisable to enter-s little more into
detail in its prevention and cure. find
that many plum trees have been CON-
pletely ruined in Maine. 1t spreads
very rapidly when once il has gained a
foothold.
The Black Knot is a fungus which
spreads by means of spores, which are
blown through the air, and if it lights in
a tree, and conditions are favorable, the
spore terminates and grows into it. In
the spring yellowish swelling appears
on the branches; little later in the sea-
son these swellings become dark in
color with a velvety surface which is
caused by innumerable spores covering
the lump or knot They in turn are
soon blown away and alight on other
branches of the tree. These germinate
and penetrate the tree as already de-
scribed, and new knots develop in time
from them. A second crop of spores is
produced in autumn or early winter, and
are liberated the following spring.
The disease is very liable to spread
from one orchard to another, which
makes it very difficult to control. To
fight the disease which is provided
with sach sure means of reproduction,
requires continuous effort until 1t is
eradicated. Trees that are badly affect
ed with the Knot had better be cut
down and burned. IL only partially
affected, the Knot should be cut off or
5 inches below the affected part and i'm
mediately destroyed. Healthy, strong
growing trees are more likely to resist
the disease than a poorly cared for tree
or one with low vitality. Spraying in
early spring time before buds germinate
is recommended by Cornell Experiment
Station as a very effectual method for
subduing the Knot, but as spraying Of
any kind is not practiced to any extent
in Maine as yet, should advise the use
of pruning shears.
Before attempting to plant plum trees
at "Sunny Beach Farm" was obliged to
cut and destroy the few remaining plum
trees on the place as they were badly in
fected with the Knot, and | also had
permission from some of my nearest
neighbors TO cut their trees also and
burn, as safeguard for the young Or
chard II is not an uncommon occur
renee in Maine to see plum trees in fruit
gardens loaded with this dread disease.
Little is known in some cases about
this subject. In my observations dur
ing the past year | found plum tree
badly infested with the Knot and dis
covered that the owner had driven nails
practically all over the trunk as a
''cure" and also to insure full crop OF
plums. | advised this gentleman to
join our fruit growers association.
The last two years, weather conditions
have been very unfavorable for prolific
plum crop, but under ordinary con-
ditions there is no fruit crop that pays
better in Maine, and quicker results are
obtained than from the apple.