The Kennewick courier-reporter. [volume] (Kennewick, Wash.) 1914-1938, 1927-03-31
GIVES DOPE
ON WEATHER
Frost Man Says Danger
Period Varies with
Development

mands an economical use of labor
and fuel and requires a knowledge
of the temperatures which cause
injury to buds and blossoms.
Growers frequently light the heat
ers too soon, in order to maintain
margin of safety, resulting in
needless burning of oil or briquets.
On the other hand, some Of the
less cautious growers wait until
the critical temperature is reached
before lighting the heaters and,
as a result, often suffer some dam
age to the buds.
From a reading Of the popular
literature on the subject one would
be led to infer that the buds and
blossoms have definite critical
temperature and when this tenn
perature is reached they all freeze.
This is wide of the truth. There is
a range of several degrees between
the highest temperature that will
kill three or four per cent Of them
and the temperature that will kill
all of them. 1t should be remem-
bered that on the same branch
are buds that have swollen but
slightly while others are in full
bloom. There is also a great diff
ference in the hardness of the
individual buds. A freeze or two
in the spring may not materially
reduce the crop for there are al
ways many times more buds than
ever mature into fruit. However,
the buds killed by the first freeze
in the spring are the ones most
advanced because as the buds ma
ture they become more susceptible
to frost injury. The killing of the
early buds would retard the matur-
ing of the fruit a few days as
the later buds would probably ma
turally be thinIed if the early buds
had not been killed.
Fruit from late bloom is usually
undersized and of poor quality. It
is very rare that tree has so few
buds that it can not loose half Of
them and yet mature a fair crop
of fruit. This sfrost thinning" is
undesirable because it is not uni
formly done. One part Of the tree
! may bear no fruit while the other
part, usually the tops, will be so
heavily loaded that thinning will
be necessary.
In the process of natural thin
ming the number of fruits on the
tree is steadily and rapidly reduc-
ed after the period of full bloom
and a loss of a large percentage
of the fruit retained on the tree
at this time is likely to reduce
seriously the size of the crop har-
vested.
The stage Of advancement is of
the greatest Importance in esti-
mating resistance to low tempera-
lures; the same degrees Of frost
that causes little or no damage to
fruit in the bud, may injure the
greater portion of the crop two
or three days, or week later. In
the case of most decidious fruit,
the same temperature will cause
far more permanent damage after
the fruit has set than during the
period of full bloom, and the later
the frost after the fruit has set,
the greater the actual loss. One
or two uninjured blossoms in each
cluster are usually sufficient for
a good crop. With cherries a larg-
er percentage Of the blooms must
mature to insure a full crop and
damage during full bloom is more
serious.
However, until some physical
measurement Of the hardness of
fruit buds is worked out tempera-
lures which buds will endure with
out being killed can not be given
definitely nor can less loss Of fruit
from spring freezing be accurately
determined.
There are so many factors which
determine the temperatures which
can be withstood by deciduous
fruit, buds and blossoms that It is
impossible to state definitely the
temperature at which damage will
occur at the various stages of de-
velopment. The average tempera-
ture, as indicated by a sheltered
thermometer placed about four and
a half feet above the ground.
which can be endured for thirty
minutes, or less, as determined
from a great many observations
covering a period of years follows:
Apples, buds closed, showing col
or, %; full bloom %; small green
fruit, 29.
Peaches, %; 26; 20.
Cherries, 25; %: 80.
Pears. 25; Is; 80.
Pluns, 25; %; 80.
Apricots, %; %: 81.
Prunes, 26; %; 80.
Grapes, 30; 81: 81.
The above table makes no pre-
tense at being complete because Il
does not cover all stages of deyel-
opment between the bud and th,
developed fruit. However. unt;l
more data is secured the abova
figures are the best obtainabIe
The fruit buds of most deciduors