Oxford Democrat. [volume] (Paris, Me.) 1833-1933, 1920-08-10
Plum Pockets.

The plant pathologist Of the Main'
Agricultural Experiment Station Cal
always depend upon crop OF one typ
of plums, and this natures very early II
the season. Numerous specimens o.
this kind of "fruit" are received from
correspondents. Like most other spec
linens of fruits and vegetables that come
to the pathologist's desk they are o
little value in reducing the high cost o
living.
Except for their general shape ont
would hardly recognize the growtbi
referred to above as originating from
plum fruits. They are commonly
known as "plum pockets or "bladdel
plums", and they are we'll named. A
short time after the blossoms fall and
before the young plums have begun to
enlarge very much, small whitish spots
begin to appear on them. These spread
rapidly over the fruit and cause 1t tc
develop In very abnormal manner. In
Maine by the middle or last Of June,
when the normal fruit may not be larger
than an ordinary bean the affected ones
have become transformed into large,
soft, bladder-like, grayish or greenish
white bodies, often an inch and balf to
two inches or more long. After short
time the abnormal growths begin to turn
dark colored and drop of.
Plum pockets are caused by para
sitic fungus growing in the tissues OF the
affected fruit. It also attacks the young
twigs and leaves, often causing them to
be enlarged and much curled and dis
torted. Frequently the leaves on the
diseased shoots of the current year turn
brown and drop off. The opinion has
been quite general that the disease lives
over winter in these infected shoots and
spreads from them to the flowers and
fruit in the spring. Hence as q control
measure, 1t has been customary to recon-
mend severe pruning to remove such
affected twigs as far as possible. II
such twigs were the sole source OF infec-
ton and infection took place as result
of the growth Of the fungus through the
tissues of the twigs till 1t reached the
young fruits, 1t is very evident that
spraying would be as effective as direct.
ing a stream of water from q fire bose
upon the roof of building in an effort
TO control fire located In the interior
partitions of the same building. Recent
work suggests that there is something in
the life history of the fungus which
causes plum pockets that the patholo-
gists have not discovered and that spray
ing at the right time is very important
means of control.
Investigations conducted independent.
ly in Minnesota and Montana indicate
that, while the fungus may live over
winter in diseased twigs, the majority of
the infections Of the young plums come
from some other source, and that spray
ing at the proper time with lime-sulphur
Is an effective means of control. Accord
ing to the Montana reports a single ap-
plication of lime-sulphur of about the
same strength as is used for summer ap.
plication to apple trees is sufficient and
that this application can be made any
time after the leaf buds begin to swell
and open, up to just before the flower
buds open.
In both Montana and Minnesota spe-
cial emphasis was laid upon the impor-
tance of the spray before blossoming to
control plum pockets and the expert
ments made In the former state indicate
that a dormant spray is very helpful
while an application made after the pet
ais have fallen is too late to do much good.
However there are other plum diseases
which require later spraying to be effect
ually controlled. 1t Is believed also that
two other recommendations made by the
Minnesota pathologists are we'll worth
being followed in Maine. These are to
prune out and burn all affected twigs
and to destroy all diseased or mummied
plums found on the trees or on the
ground beneath them.-Chas. D. Woods,
Director.