Bennington semi-weekly banner. (Bennington, Vt.) 1894-1902, 1894-07-10
CORRESPONDENCE.
USING the Bordeaux Mixture.

Inc Agricultural EXPERIMENT. SCdJlOn
has issued the following explanatory
and timely bulletin. in response to a de-
mand among the farmers of the State.
There is no use of talking, something OF
this kind must be done, or the crop is a
failure henceforth. ED.
DEAR SIR:-So many are lnquirlng
about spraying potatoes for blight that
it seems best to issue another circular
letter giving directions for the use of
Bordeaux mixture. We are satisfied
after five years experience that it pays
to spray all potatoes in Vermont with
this mixture.
Our potato vines are attacked by two
distinct blights. The early blight at
acks earlier potatoes, spreading slowing
in July and August, causing premature
death of vines but no rot, The late
blight attacks later potatoes in August
and September, spreading rapidly in
warm, moist weather, and is followed by
rot. The early blight is complex
trouble caused by the attacks of insects
as well as fungi. 1t is already appearing
on early potatoes. Being a complicated
disease, it is less perfectly controlled by
spraying than is the late blight. Our re-
suits last summer showed that it can be
at least partially checked by Bordeaux
mixture. The late blight and rot is a
fungous disease, and Bordeaux mixture
properly applied is an almost perfect
remedy. By its use we have invariably
kept our later potatoes alive through
September and have lost but very few
from rot. The result has been that our
yield of later potatoes has been more than
doubled by spraying. Every potato
grower should try it this summer es-
peoially on medium and late potatoes.
The formula for Bordeaux mixture is:
Five pounds copper sulphate, five pounds
lime Unjust be fresh, not air slacked),
fifty gallons Il barely water. Dissolve
copper sulphate in clean wooden or brass
vessel, slack the lime in another vessel,
then dilute with water to thin white
wash and STRAIN it into the copper sOlu-
ton. Stir thoroughly and add water to
make about fifty gallons Il barreD
The following suggestions may prove
of use;
l. Keep yOur mixture clean. Chips,
Jumps of lime, ETC., in the mixture clog
pump or nozzles. Therefore, thorough
ly clean all vessels to begin with.
Strain all water and copper solutions
through cheese-cloth unless they are per-
fectly clean. Strain the lime whitewash
through some coarser cloth or sieve and
throw away all the dregs and Jumps.
2. To diSSOlUe Blue Fitriol. 1t may be
quickly dissolved in water by heating in
brass ksttle to the boiling point, or by
pouring boiling water over it. The most
convenient way we have found, however,
is to dissolve in cold water by putting it
in coarse sack and suspending this in
the top of tub or barrel of water. AS
fast as the heavy solution forms it set
ties to the bottom and fresh water rises.
BY using a gallon of water for each
pound of blue vitriol it will dissolve in a
few hours in this way.
3. Keep a Stock Solution. We find it
most convenient to dissolve considerable
blue vitriol at time in the above man
ner, and to keep it on hand in covered
barrel. We put in pound of vitriol for
each gallon of water, and as we wish it
from time to time we simply stir it up
and dip out as many gallons of the solu-
ton as we wish to use pounds of blue
vitriol.
4, Other convenient methods. To
avoid the trouble of weighing the blue
vitriol may be measured out five pounds
equals Gwo quarts), and the lime added
by test. This test consists in pouring a
few drops of solution of ferro cyanide of
potassium Il OF. in OF. water) into the
mixture. If there is not enough lime in
the mixture this solution will at once
turn brick-red, but if enough lime has
been added there will be no change of
color.
5. Caution, Strong copper sulphate
alone will kill the leaves. Freshly slack
ed lime neutralizes the sulphate and pre-
vents this caustic action. If not sure
that the lime is fresh or good, or that
enough is added, the mixture should be
be tested as described in 4, or a few
plants only should be sprayed at first TO
to test its action.
6. Potato Beetles. Bordeaux mixture
alone will not kill the potato bugs. Add
paris green when needed at rate of ]
pound to 80 gallons.
7. When to Spray, Remember that
Bordeaux mixture is preventative not a
cure, and the first application should be
made before the disease appears. The
following dates for spraying potatoes
based on our experience at Burlington:
Early potatoes planted April to May 5
spray about July l, 10, August l, and
again if needed.
Medium potatoes planted May 8 to
May 10 spray July 10, August l, Is, and
again if needed.
Late potatoes planted May 10 or later
spray about Aug. l. Aug. IA, Aug. rs
and again if needed.
8. HO,U to apply it, The mixture may
be put on in any way so as to cover the
upper surface of all the leaves. The
best way to do this is with force pump
which has good spraying nozzles attach
ed. Unfortunately, but few have these
pumps. Applying with a common
pot or with pail and broom
or wisp of hay takes more time and pa
tience, as well as more of the mixture,
and if thoroughly done will give good re-
suits. In most cases where watering
pot is used it will work better if the
holes are enlarged with an awl. Apply
thoroughly it will not injure the vines,
the mixture has been properly
made.
Further information will be freely
given in answer to any letters of inquiry.
/. r. JONES, Botanist,
Experiment Station, Burlington, vt.