Rogue River courier. (Grants Pass, Or.) 1886-1927, 1910-12-02

twigs or water sprouts. Blight occa-
sionally enters by the third method
directly into the tender, growing,
fleshy bark, through growth cracks,
although as a general rule this meth
cd of entry is comparatively rare.
Sapsuckers or woodpeckers become
infected by puncturlng cases of hold
over blight, and afterward visiting
healthy trees produce blight infection |
in them. We have several obserya-
tions along this line, and doubtless
many more occur in nature. 1t is
even possible for the whiffletrees or
implements used in cultivation to
transfer the infection; pruning tools
are certainly very frequent cause
of transmitting the disease, especially
during the growing season.
Mr. Waite states that in Maryland
he saw a nursery block of 10000
Bartlett pear trees completely de-
stroyed by blight This block, aS was
determined by the specimens, carried
actual samples of holdover blight in
the stocks. When stocks were cut
off above the dormant buds in the
spring, the pruning tools became in
fected and the disease was transmit
ted to nearly every tree reached by
the pruner. Instead of the buds push
ing up, the cut surface began to gum
cases and blight. The writer has seen
in certain nurseries in Nebraska
many cases where nursery infection
has been brought about through the
use of tools which have been used in
cutting out blight infection in large
orchard trees, without previously
disinfecting them. Pear blight be-
haves in all sorts of irregular ways
, when It runs down the limbs and
branches. Occasionally fruit spur
blighting causes the disease to spread
in a circular spot an inch or two in
diameter on the branches. More Of
ten It is an ellipticai spot extending
J lengthwise Of the branch. It may
run down in long line from the low
r er edge, making 1t very difficult tt
= save the branch or even the tree It
self by cutting, on account Of thi'
: narrow strip Of the disease. 1t II
= almost impossible to anticipate thu
= variations in behavior of the disease
, because 1t depends upon so many diff
y ferent factors It may be well t
e point out some Of the factors control
e ling the habits of the disease in or
e der that you may see how varied ar
y the influences controlling It.
: These factors may be divided NOR
i or less completely into two sets
y First, those which govern infection
5 and second, those which determin
t. the spread Of the blight in the tire
s. after infection.
u The first factor is the presence {
'e the bacillus. The pear blight gerl
a must be present in the orchard {
" must be carried there during tn
~ season in order to have the bligh
% No matter how favorable the cond
~ tions may be, unless the germ
Is there the disease can not develo
- The immunity Of California and Or
o. gon orchards up to recent years,
g course, is attributed to the fact TIL
&c the germ was not there. The secoI
W factor Is the number OF insect visito
" We have pointed out that insec
20 carry the blight about. The hon
'u bee is one Of the most active in ca
II ryng the blight on the blossoms, OF
% er insects visit the pear and apr
nc blossoms and carry the blight We
oe widely. The presence OF some ct
30 tain species OF insects as already su
nu gested, has been the means Of intr
NC ducing the blight into the twigs a
~ branches or bodies OF the trees. n
Wy only must the insect be present a
a' the germs there for them to car
''' but the weather conditions must
'ne favorable for the activity Of the
e' sects and to bring the trees into pre-
ne er condition for infection.
ith
~. Flower-visiting insects usua
like sunshiny weather, especially S,
D., ny weather following a moist seas
AZ, which allows many kinds to ha
- out or develop from pupa, Yor
A., orchards are not usually attacked
- the blight, rather rarely in fact, III
they have blossomed, unless there
bad attack of blight in a pear
ea' other pome fruit orchard near
Ut" hand There are some cases of yol
i"e orchards which | have seen in c
'no formnia and Oregon that have bills
Ple ed somewhate seriously before I
e''' had bloomed, but they were ale
'u.e side badly blighted pear orcha
WI" The presence OF water sprouts
Y