Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1920-10-20
Of LATE
BLIGHT OF POTATOES

compared with the Bordeaux
Mixture - Cooperative Ex-
periments on ArOostook
Farm Prove Very Successful
--Composition Of the Two
Mixtures.
Orono. Me-. Oct. 19-The following
i! was made public this afternoon by
Charles D. Woods. director of the
Maine Agricultural Experiment
station:
! For more than twenty-five years
the Maine Agricultural Experiment
Station has been investigating potato
diseases and their control. The late
blight which is so often followed by
trot was the. worst fungous trouble
twenty years ago. The cfrectual con-
troll Of this disease was shown to be
practicable by tho thorough appli-
cation Of properly prepared Bordeaux
mixture. The efficiency Of Bordeaux
mixture depends upon tho : copper
that 1t carries. When in 1915 tho
price Of copper sulphatc rose so
greatly the Federal Bureaus Of
Chemistry and Plant Industry, in Coz
operation with the Maine Station
began studies looking toward a lower
cost fungicide than Bordeaux mix
ture. Previous investigation had
failed to discover any fungicide
which could replace copper sprays
for late blight Of potatoes. AS the
search for a new spray seemed I'M
promising It seemed advisable to
seek for a copper spray which should
be more effective per unit Of copper
than the standard Bordeaux mixture
and at the same time not sufficiently
caustic to injurc foliage.
i A. spray to be effective must 80
distribute the copper compound It
contains as TO completely cover tho
leaves Of tho potato plant in a thor
oughly uniform manner and must
possess the proper adhesive qualities.
Lacking either Of thcao qualities the
spray fails to protect the plant from
the fungus.
Lime 10 only slightly -solub1o in
water. When. quick hnae 10 Stacked
with an abundance Of water and is
allowed to stand most of the Stacked
limo settles to the bottom. The water
above this will however contain a
small amount Of limo in solution
This solution ia made and sold at
drug stores as Lime water" If the
sediment that settles is stirred thor
ouGhiy it is mechanically suspended
IN the water and 10 known as milk
of Lime. Bordeaux mixture 10 made
from dissolved copper nulphatc and
tho milk OF lime. At tho Woburn
England Experiment Fruit Farm
copper sulphnto and 2sli..:o water.
These were called, from tho ;,aT11o OF
the investigator. Pickering npra. 80,
and limited work in England showed
them in some particulars superior to
standard Bordeaux mixture made
with the milk of lime. 1t was
claimed and corroberatede: 10y other
Investigators. that Pickering sprays
remain in suspension far better and
longer than standard Bordeaux mix
lures. that they have larger cover
foliage does not deterieratc as fast
as that from standard bordeaux, that
it acts moro quickly, il FREQ from
= gritty particles. On the other hand,
az tried out in Victoria. (Austrnlin).
the Pickering spray was found in
fcrior to 2 per, cent standard Dor
deaux mixture.
With all these more or less conflict
inE data and with the thought in
mind that II the reCults obtained by
Pickering under laboratory condi-
der American field conditions grea.
saving in copper would result, the in
vcstigation by tho Federal Depart
ment of Agriculture waa planned in
cooperation with the Maine Station.
Tho experiments were conducted
with, the following primary objects:
10 determine whether Pickering
pays were effective when. applied
~ potatoes under Maine field con-
tsitcns. To ascertain how much
copper is required in the Pickering
sprays to insure. effective control of
fate blight. To compare the fungi
Cidal value Of the Pickering sprays
with the standard Bordeaux mixture
per unit of copper; to determine the
amount of foliage injury from the
Pickering sprays as compared with
standard BORDEAUX and to compare
the adherence Of Pickering sprays
with standard Bordeaux.
The results of these studies have
been published in the technical
bulletin $3.50 of the United States De
partment of Agriculture. This bulle-
tin is not available for general dis
tribution. The following is brief
summary Of the results.
In the ordinary $3.50 Bordeaux
there is about 1.25 per cent of copper
present In the most effective Pick
ering solution there is 4 per cent
copper present.
In three seasons work In the con-
troll OF late blight on potatoes a Pick
ering spray containing Z per
cent of copper sulphate controlled
the late blight as well and
gave yields equal to those obtained
with a 6-5-50 Bordeaux contain
ing 1.25 per cent copper sulphate.
The copper in the Pickering spray
was apparently. weight for weight,
nearly twice as effective as that in
the standard Bordeaux. There was
no injury to the vines Of tubers from
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