Middlebury register. (Middlebury, Vt.) 1886-1937, 1894-07-13
SPRAYING
FURTHER INFORMATION FROM THE Ex-
PERTINENT STATION.
BURLINGTON, W., July I, 1871.

inquiring about spraying potatoesi Tor
the blight that it seems best to issue an
other 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
tacks earlier potatoes, spreading slowly
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 isGfol-
lowed by rot. The early blight is a
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 results last summer showed
that it can be at least partially checked by
Bordeaux mixture. The late blight and
rot is a i%fungous disease and Bordeaux
mixture properly applied is an almost
perfect remedy. BY its use we have in
variably 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 on spraying. Every
potato grower should try it this sum
mer. especially on medium and late po-
tatoes.
The formula for Bordeaux mixture
is: Five pounds copper sulphate' five
pounds lime (must be fresh, not air
slacked), fifty gallons Gone barrel) wa
ter. Dissolve the copper sulphate in
clean wooden or brass vessel, slack the
lime in another vessel, then dilute with
water to a hin whltewash and strain it
into the copper solution. Stir thorough
w and add water to make about fifty
gallons Gone barrel).
The following suggestions may prove
OF use:
/. Keep your mirtuTe cleoR. Chips, Jumps
of lime, etc. in the mixture will 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.
=. To diSsolre blue rih1ol. 1t may be
quickly dissolved in water by heating in
a brass kettle 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 a coarse sack and suspend
ing this in the top of a tub or "A barrel of
water. As fast as the heavy solution
forms it settles to the bottom aud fresh
water rises. By using a gallon of water
tor each pound of blue vitriol it Twill
dissolve in a few hours in this way.
3. KecDa stock solution. We find it most
convenient to dissolve considerable blue
vitriol at a time in the above manner and
to keep it on hand in a covered barrel.
We put IN Il pound of vitriol for each
gallon of water, and as we wish it from
time to time we simply stir 1t up and dip
out as many gallons of the solution as
we wish to use pounds of blue vitrlOl.
4. Other Convenient methods. To avoid
the trouble of weighing. the blue yitriol
may be measured out Give pounds equal
two quarts. and the lime added by test.
This test consists in pouring Il few drops
OF solution of ferrO-cydnide of potas-
stun {, on. in 4 or. water into the mix
ture. 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.
D.. Caution. Strong copper sulphate
solution alone will kill the leaves.
Freshly Stacked lime neutralizes the sui
piIate and prevents TINS caustlc action.
If not sure that the lime is fresh and
good, or that enough is added, the mix
ture should be tested as described in 1,
or a few plants only should be sprayed
at first to test its action.
6. Potato beetles. Bordeaux mixture
alone will not kill the potato bugs. Add
paris green when needed at rate of one-
half pound to fifty gallons.
4. When to spray. Remember that
Bordeaux mixture is a preventive, not a
cure, and the first application should be
made before the disease appears. The
following dates for spraying potatoes
are based on our experience at Burling-
ton:
Early potatoes planted April to May
SPRAY about July l, Is, Aug. /, and
again if needed.
Medium potatoes planted May > to
May l5-spray about July Is, Aug. l,
Il, and again if needed.
Late potatoes planted May Is or later
spray about Aug. l, Aug. II, Aug. IS
and again if needed.
S. How to apply il. The mixture may
be put on in any way so as to cover the
upper surface of all the leaves. The
hest way to do this is with a force pump