The Manchester journal. [volume] (Manchester, Vt.) 1861-current, 1917-07-19
MARNING TO POTATO GROWERS


week have been very favorable TO the
development Of the late blight Of the
potato A careful examination by the
Agricultural Extension Service OF the
State University, Of potato plants
from plots in Burlington has shown
the disease on some Of the leaves,
The disease appears as irregular dead,
shiivelled, brown spots on the edges
or sides Of the lower leaves, especially
those leaves in contact with the soil.
The weather conditions at Burlington
(high temperature and humidity have
probably been fairly general through
out the State. A general late blight
infection is therefore TO be feared, and
growers of potatocs--whother on city
lots or in tields--arc warned of the
danger to their crop unless spraying
with Bordeaux mixture is carried out
as soon as possible.
Treatment
The Spray Mixture.--No better
compound has been discovered with
which to combat potato diseases than
home Bordeaux mixture. II is
made Of copper sulphate (blue vitrioD,
water Stacked lime and water. 1t is
only a fungicide and docs not kill the
Colorado potato beetle. II combined
with Paris green or arsenate of lead,
both insect and fungus are attacked.
Paris green is quicker in its action
than arsenate Of lead, but washes off
more readily and is most costly.
Either works we'll Both adhere to
the foliage much longer II applied in
connection with the Bordeaux mixture.
The spray mixture should be made as
follows:
Dissolve 30 lbs. copper sulphate in
30 gallons Of water in wooden vessel
by suspending the crystals in sack
over night Slack 80 lbs. lime with
water and add enough to make 30 gals
Ions. These arc the stock solutions.
They may be prepared at the begin
ming of the season and will keep in-
definitely, but must not be mixed until
/ the day they Are to be used On the
day the spraying is to be done, put
three gallons Of the blue vitriol soIu-
tion in separate container and dilute
this to approximately 20 gallons. Put
| three gallons Of the lime solution in
another container and dilute this to
20 gallons. Then mix the two solu-
tions, stirring rapidly as they are
| poured together. The mixture should
be strained through sack or piece Of
cheese cloth to remove lime particles.
Stir y pound of Paris green (or u
lbs. dry arsenate of lead) in little
water until it forms paste and add 4
part to each barrel of the mixture.
Then add water enough to bring the
whole to so gallons.
Time of Appl:cation.--The first APP
plication should be made when the
newly hatched potato bugs" are seen
or the flower buds appear, usually
the first week. in July. The foliage,
especially the lower leaves, should be
thoroughly covered Other applica-
tions should be made at intervals Of
about two weeks. An application
about September 1st is especially de-
sirable since late blight epidemics at
this time are usually followed by de-
structive potato rots.
Cost Of Materials.-Two barrels TO
the acre should be used, costing:
3 lbs. of copper sulphate at 1Sc, $0.54
11a lbs. of Paris green at 55c. -. 0.83
8 pounds of lime at lc. ......... DOB
One application ............ $l.4O
Four applications .......... $3.50
The Results. - Bordeaux-arsenical
spraying, If properly conducted, in
sures the crop against blight and
beetles. No bank should loan money
on potatoes that are not thus cared
for. The protection against early
death from tip-burn and flea beetle in
jury will repay the cost Of the spray
;,,, ;r ya,re uhen mn hliuht occurs