The Washburn leader. [volume] (Washburn, McLean County, N.D.) 1890-1986, 1901-06-15
FARM AND GARDEN.
MATTERS or INTEREST TO
AoRlcULTuRlsTA

ACKNOWLEDGEMENTS.
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New Light. On Pear BlsgAk
Pear blight has up to this time, been
Q thing shrouded in q good deal OF
mystery. Efforts to check or eradicate
it have been so generally unsuccessful
that many growers Of pears have come
to believe 1t an enemy too subtle to
be avoided. The real difficulty doubt
less has been our ignorance OF It's
methods Of attack. The Delaware Ex-
peri ment Station has been doing some
good work along the line of,fndtng OUT
Just how the blight attacks the pears
and pear trees. The tests made on
sisted, in inoculating the pear tree IN
its various parts with pure cultures OF
blight germs. A sterilized needle was
dipped into a culture and then used In
puncturing a part on June 9, lsoo' AZ
follows:
/. Present years terminal shoots
by p%uncture.
2. The previous years wood BY
puncture.
8. Three years old wood by pune
ture.
A. Buds by puncture.
s. Leaves by puncture.
6. Fruit by puncture.
z. Leaves smeared with q broth
ture and covered with paper bags to
keep of insects.
g.. Leaves wet with distilled water.
and covered with paper bags (check).
9. Present years terminal shoots
smeared with a broth culture, n COW
erred with bags.
The points Of incubation IN all
cases were covered with several layers
Of wet h%lter-paper. and the papers tied
on with bands Of wet cotton cloth.
We condense the notes Of results as
taken three weeks later: ~ Twig
blighted. (2) No result. (3) Only q
minute surface blighted around pune
ture. ~ Buds blighted. (5) One Leaf
blighted over one-fourth Of its surface;
others showed only minute blight
spots. (6) Fruits blighted badly. ~
No result. (s) No b~lackening. G9) No
result
The preceding experiments show: !.
lThat q become infected only by
direct incubation, and the introduc-
ltion Of the virus, and that no infec
ton results from contact OF the germ
with an uninjured surface.
O. That only the more tender and
succulent parts become infected IN this
Emanner. such as leaves. succuient
shoots. buds and fruit, and that older,
even second year wood. is not liable
to become infected even when injured
or punctured.
3. That the mechanical contact OF
..blighted parts with those which are
healthy and uninfected is not likely
to result in infection.
Each independent member OF tae
plant must therefore become separately
infected in the manner indicated. The
germ may Of course enter some tender
terminal growth and from this point
extend downward, often with consid-
cradle rapidity, 80 a to involve On
entire limb. But even here the In
Movement Of an entire limb II more
likely to imply the multiple infection
Of terminal growths attached TO this
limb. The rate Of the extension Of
blight is much more rapid in the more
%succulent than in the harder wood.
1.-THE disease appears to spread slowly
in older wood. sufficiently 30 at any
rate. to give the fruit-grower time
enough to cut of the diseased term
inal shoots before the malady has ex-
tended downward to the large limbs.
The Control Of. Pear Blight-In ad-
dition to this early pruning It Is i'm
portant to go through the orchard in
the fall, while the leaves + still ca
pable Of showing the effects Of blight.
and removing any blighted branches
In cutting It is important to remove
the limb some inches below the line
Of blight; the cut ends should then BIZ
painted to prevent fresh infection.
There can be no doubt but that grow
ers fail to watch their trees closely
enough, and thus to check the disease
before It has done marked damage. A
primary factor IN the control consists Il
the pruning Of the blighted terminals
before large limbs which have taken
years To form have been invnlved. The