Corvallis gazette. [volume] (Corvallis, Benton County, Or.) 1900-1909, 1906-04-03
SAN JOSE SCALE.
Excerpt From OAC Bulletin by
Prof. A. B. CordIey

owing to its small size and in
conspicuous color, it often re-
mains unnoticed until the tree
has been seriously I'M ured or even
killed. That the tree lacks vigor
may be recognized, but the cause
of its unthriftiness is overlooked.
Yet it is not difficult to detect
when one really looks for it.
In the early stage of infestation
a few scales may be found, usual
ly clustered about the buds of tn
preceding seasons growth, or
even on two year old wood. Th
mature scales are grayish in
color, being usually but not
always somewhat lighter than
the bark to which they are So
closely attached. The immature
half-grown scales which may be
found with the mature ones, are
at the present time somewhat
darker in color.
The mature females are nearly
circular in shape, are approx
mately one-sixteenth inch in di-
ameter and each is so mewhat
raised in the center to form a
slight protuberance or nipple
which is lighter in color than the
rest of the scale. If this scale is
carefully examined by means OF
a small magnifer several con-
centric circles may be observed
between the nipple and the out
side edge, and if it be carefully
raised with the point of a pin or
knife there will be revealed a
miniature bright yellow object,
the insect itself.
On badly infested plauts the
young scales settle wherever
there is room to insert a beak
into the bark aud as they in
crease in size they become much
crowded and overlapped and have
the appearance of a gray scurv>
deposit on the bark. The natural
color of the bark is obscured and
the infested plant appears as
though coated with hue ash
colored bran. If the thumb
nail or other object is rubbed
over this scurvy covering, there
by crushing the insects beneath
the scales, moist or oily appear
ance is produced and numerous
scales will be overturned and
many of the little yellow insects
be revealed.
During the early stages of au
attack very few if any of the
scales will settle upon the leaves
or fruit. Later both may be at
tackled. Upon the leaves, espec-
tally of the prune and peach, the
young scales may be found on
bo b surfaces aud more par
ticularly clustered along the
midrib. Each scale produces a
minute purple spot. Upon
purple prunes, red apples, etc.,
the scales appear only as minute
gray specks usually clustered
about the cavities at either end,
but upon the yellow fruits like
pears, peaches, and the yello "
plums and apples, each scale pro-
duces a bright reddish discolor-
alton. If badly infested, the
fruit, particularly of pears and
apples, become much pitted,
distorted in shape, cracked and
unmarketable.
For the benefit of fruit inspec-
tors in particular, it should be
noted that the reddish discolo1-
ations upon the yellow fruits are
not always caused by San Jose
scale. Upon yellow apples and
particularly upon peaches very
similar spots are produced by at
tacks of certain minute fungi.
Hence, such spots should not in
themselves be taken as proof OF
infestation by the scale. This
can be determined definitely
only by carefully examination
and the actual detection of the
sale. The presence of such
blotches may we'll arouse sus-
picion of the presence "f San
Jose scale and should challenges
a careful examinat On alila By
growers, buyers and inspector; so
also should the presence OF
dead and shriveled leaves upou