Pullman herald. [volume] (Pullman, W.T. [Wash.]) 1888-1989, 1912-07-12
Scab in Orchards

| presumably because of the con-
tinued cool and rainy weather imme-
diately following the blossoming
period orchards of this locality are
this season more than ordinarily af-
fected with apple scab. Because of
this condition the following, taken
from Better Fruit" and dealing in
telligently with the scab pest, should
be of interest to local orchardists:
Apple scab is a fungus disease of
the fruit and foliage of the apple,
and ranks as the most destructive
disease to which this fruit is subject.
In unsprayed orchards it often
causes the loss of so to rs per cent
of the crop, and not infrequently the
entire crop of certain varieties is
rendered unfit for market by the de-
| formed, cracked and unsi Chilly condi-
ton produced by the fungus. At
fected fruit is usually small, insight
| ly, often cracked and does not keep
well. However, since the practice of
spraying has become general among
apple growers this condition has
been largely relieved. Apple scab
| is common practically wherever the
apple is grown-in America, Europe,
Australia, New Zealand and else
where. However, it is essentially
cool climate disease, and in the
United States it is most destructive
| in New England, the middle Atlantic
States, the Great Lakes region, the
Mississippi and Ohio Valleys and por-
tons of the Pacific Northwest. In
| the Southern states it is not seri-
out pest except on the higher eleva-
tons, and then only on very suscept-
ible varieties. The fungus causing
apple scab attacks the fruit and foil
age, and to a much less extent the
twig. The greatest damage is done
to the fruit, on which it produces the
scabby spots familiar to most apple
growers. These spots are circular
though somewhat irregular in out
line, dark gray or oliyaceous in color.
becoming blackish with age, and
they range in size from mere specks
to spots one-fourth inch, Nor some
times one-half inch, in diameter.
The fungus ruptures the epidermis
of the apple, forcing a gray, jagged
ring at the border of the healthy It's
sues. Two or more spots may coal
esce. forming a large scabby area, IN
some cases covering one side OF the
ample. This disease prevents nor
NAL growth of the fruit, the affected
side becoming dwarfed, pitted ana
otherwise deformed. 1t also causes
the development of cracks, when
NAV extend half way around the ap-
ple and almost to the core. A large
percentage of the affected fruit drops
to the ground before maturing In
cool, wet spring the blossom buds
and young fruits in blossom may De
|
attacked and destroyed. Occasional
", though rarely. the entire crop OF
an important fruit section may be de-
stroyed in this manner. The disease
occurs on both sides of the leaves
forming smoke-brown or ohvaceous
patches which become swollen anu
blister like. The affected leaves Oh
ten curl somewhat and may drop
prematurely. The fungus is SAID 10
occur also on the twigs, forming
blackish- olive patches, but TINS Is APP
parently not common in the unlteu
States. Apple seab is caused by d
fungus known as Ventura POM
Whit, which lives over winter IN inc
fallen apple leaves. In the SPRING
when the weather becomes warm
enough to start it the fungus De-
comes active, producing large mum
hers of spores, which are dischargeu
Into the air and carried to the young