The Emmett index. [volume] (Emmett, Idaho) 1893-1925, 1922-06-01
TREATMENT OF APPLE
MILDEW
Careful Pruning and Spraying Of
Trees Recommended to
Control Disease.
lBy E. E. Deanl

Il Owingto the fact that Apple Powd
cry Mildew made its appearance il
the Emmett district last year and di
some damage which in some instance
undoubtedly will show in this year
crop Of some varieties, especially tn,
Jonathan because it appears to b,
more susceptible to the ravages O.
this fungus, and because Of the many
and varied opinions Of this fungi.
| growth among the growers, there hal
been considerable discussion recently
concerning it and we are afraid thai
many do not fully realize the Vita
necessity TO all fruit growers to con-
troll this disease
The fungus causing powdery mil
which have formed on last years in
fected twigs. 1t is therefore out of
reach Of any spray that van be ap-
piled before the buds open. As soon
as the leaves appear the fungus be-
gins to work and in short time pro-
duces spores which continue to spread
it turnout the growing season. 1t is
a great help in securing control Of
this fungus il all the infected twigs of
last year can be cut out in the win
ter's pruning. The disease cannot be
completely controlled in this manner
because there are insulated buds scat
tered over the trees which are infect
ed, but cannot be easily detected at
this time. However, the whitened
twigs which carry the main crop of
infected material can be easily seen
and they should be cut wherever prac-
ticable. This fungus can not be en-
tirely controlled in this way, but this,
followed by carefully planned and
executed summer spraying program,
will effectually control this disease.
Many growers who are not familiar
with this fungus disease are not
aware Of the importance of its con-
troll or the bearing its non-control
will have on the 1923 crop, and are
TOO ready, to make themselves believe
ts control is Of little economic inn
Dortance.
Apple powdery mildew is caused by
/ fungus which grows upon the
caves, tender twigs, blossoms and
N the apple itself. The felt like
overing OF fungus threads over these
PARTS sends down at frequent inter
-als tiny suckers" which invade the
ellis Of the twigs, foliage and fruit.
these Suckers" extract the apple
uice for the sustenance Of the fun
us. To propagate itself the fungus
reduces millions of spores which are
distributed by the wind to other parts
( the orchard. II one of these spores
odges upon the tender growth where
ecessary moisture is present it will
immediately terminate and start q
ew infection 80,
We must not believe that it requires
xcessive rains or heavy fog 10 pro- !
ucs nildsw, but to the contrary this
un9ux has very low moisture re- |
uirement for spore termination and !
IS therefore adapted itself to rapid
rowth in the arid sections where
Their fungus such as apple scab and t
nthracnose have not been able to ,
ersist Occasional light rains in I
Re spring are sufficient to give it a
tart and the prevalence of dews, such
5 we find in this district, coupled :
18th the humidity in our orchards q
,uaed by irrigation necessary to |
row cover crops and fruit during the
immer, provides sufficient moisture q
,r its continued spread. ~
The disease first manifests itself in
nall feltlike grayish patches usual .
on the under side of the tender
'liage, which soon becomes curled
I'd crinkled Young leaves become
arrow and elongated and very soon
is growth spreads and covers the
tire leaf and the tender twigs. This
ops the growth of the twigs and
e foliage ceases to function and be- q
mes brittle, which devitalizes the II
ee and greatly lessons both the =
Iantity and the quality of the fruit. r
lie disease also attacks the yonng J:
nit buds which form during the lat a
r part Of the growing season to
ch an extent as to greatly eliminate n
e next seasons blossom. q
Apple powdery mildew is not hard !,
control If proper methods are en-
Dyed and strict adherence is given q
time of application. Federal and II
ate experiment station experts all
rec that this disease is best con- n
oiled with lime sulphur solution, but I,
ne sulfur solution or any other sui ~
r solution when used in hot weather
the arid districts, must be used n
tn degree of caution. When sui te
r sprays are used during the hot G
VS. Of july and August burning Of 6
Q fruit is likely to result, therefore 8
is essential that the use of sulfur n
rays be begun early in the growing N
ason to properly stone" the tree n
so that the tree and fruit may
thstand the resultant injury which al
,uld be in evidence if the earlier m
plications were not made. Lime a,
fur solution may be safely COM
ned with Arsenate of Lead and the
flowing schedule should be employ
In cases of severe Indications the =
st application should be made when OF
e cluster-buds begin to show pink" II
ing lime sulfur at the rate Of 6h IN
lions to a 200-gallon tank, combined IL
tn the Arsenate of lead soray. II OF
e orchard temperature, in the shade, ls
above 80 degrees cut the quantity !.
4 gallons.
In each Of the following lead sprays ),
e gallons of lime sulfur to each =
0-gallon tank until the ravages of !
pile powdery mildew have been y
ecked, which will usually be after u
e third Of fourth application. II n
matte conditions are such as to be