• TABLE OF CONTENTS
HIDE
 Title Page
 Table of Contents
 Summary
 Introduction
 Character of the disease
 Fruit inspection
 Cause of the disease
 Spraying experiments
 Irrigation
 Nitrate of soda
 Picking and packing the fruit
 Control














Group Title: Bulletin - University of Florida. Agricultural Experiment Station ; no. 121
Title: Cucumber rot
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00027284/00001
 Material Information
Title: Cucumber rot
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: p. 95-109 : ill. ; 23 cm.
Language: English
Creator: Burger, O. F ( Owen Francis ), 1885-1928
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1914
 Subjects
Subject: Cucumbers -- Diseases and pests -- Florida   ( lcsh )
Cucumbers -- Diseases and pests -- Control -- Florida   ( lcsh )
Bacterial diseases of plants -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by O.F. Burger.
General Note: Cover title.
Funding: Bulletin (University of Florida. Agricultural Experiment Station)
 Record Information
Bibliographic ID: UF00027284
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000921882
oclc - 18161211
notis - AEN2350

Table of Contents
    Title Page
        Page 95
    Table of Contents
        Page 96
    Summary
        Page 96
    Introduction
        Page 97
    Character of the disease
        Page 98
    Fruit inspection
        Page 98
        Page 99
        Page 100
    Cause of the disease
        Page 101
        Page 102
        Page 103
        Page 104
    Spraying experiments
        Page 105
    Irrigation
        Page 106
    Nitrate of soda
        Page 106
    Picking and packing the fruit
        Page 107
    Control
        Page 108
        Page 109
Full Text



BULLETIN 121 -:. -FEBRUARY, 1914

UNIVERSITY .OF FLORIDA


Florida

Agricultural Experiment Station


CUCUMBER ROT
PY

O. F BURGER

-I


Fig. 37-Naturally infected cucumber leaf.

The Station Bulletins will be sent free upon application to the Experiment
Station, Gainesville, Fla.
THE E. O. PAINTER PRINTING CO.. DE LAND. FLA.





















CONTENTS
Page
Introduction ---- --- --_-__-___-- _- --- 97
Character of the Disease ---------- ------_------------------- 98
Fruit Infection -----------------------_---------------- -- 98
Cause of the Disease -- --------------__ ------------------- 101
Isolation of Bacteria -------------------------_-------------- 101
Preliminary Tests --------------------------------------- 102
Inoculations -------------------------------------------------- 102
The Bacillus --------------------------------------- ---- 104
Spraying Experiments ---------------------- 105
Irrigation -------------------------------------- -------- 106
Nitrate of Soda -------------------------------------------- 106
Picking and Packing the Fruit ---------------------------------------107
Control ---------------------------------------------- 108
Bordeaux Mixture ----------------------------------------------- 108




SUMMARY

z. Cucumber Rot is caused by a bacterium.
2. The disease attacks the leaves, as well as all stages of the fruit.
3. Spraying with Bordeaux mixture (4-6-50 formula) checks the disease.
4. Rot on the way to market is caused by packing infected cucumbers.
5. Nitrate of soda causes a soft cuclimber which does not stand shipment.
6. The cull piles should be removed from the cucumber field.





















CONTENTS
Page
Introduction ---- --- --_-__-___-- _- --- 97
Character of the Disease ---------- ------_------------------- 98
Fruit Infection -----------------------_---------------- -- 98
Cause of the Disease -- --------------__ ------------------- 101
Isolation of Bacteria -------------------------_-------------- 101
Preliminary Tests --------------------------------------- 102
Inoculations -------------------------------------------------- 102
The Bacillus --------------------------------------- ---- 104
Spraying Experiments ---------------------- 105
Irrigation -------------------------------------- -------- 106
Nitrate of Soda -------------------------------------------- 106
Picking and Packing the Fruit ---------------------------------------107
Control ---------------------------------------------- 108
Bordeaux Mixture ----------------------------------------------- 108




SUMMARY

z. Cucumber Rot is caused by a bacterium.
2. The disease attacks the leaves, as well as all stages of the fruit.
3. Spraying with Bordeaux mixture (4-6-50 formula) checks the disease.
4. Rot on the way to market is caused by packing infected cucumbers.
5. Nitrate of soda causes a soft cuclimber which does not stand shipment.
6. The cull piles should be removed from the cucumber field.












CUCUMBER ROT

BY O. F. BURGER

The growing of cucumbers for the early spring market has
become quite a large industry in Florida. In the Biennial Re-
port of the State Department of Agriculture for 1911-12, the
cucumber crop of the State was valued at $344,423. The num-
ber of acres planted was estimated to be 2,081. In Alachua
and Levy counties alone there were 982 acres grown. The
seed is planted from the middle of February until about the
early part of April. The shipping season lasts from the middle
of April until about the middle of June. A season's picking for
one planting lasts from twenty to thirty days. An acre of cu-
cumbers produces from 100 to 300 baskets, depending on the
climatic conditions and the prevalence of diseases. A basket
holds about three-fourths of a bushel, or about Ioo to Ino fancy
cucumbers. The cost of production is estimated at about $90
an acre, including picking and packing.
The most important cucumber troubles are: (i) Blight,
(2) bacterial rot, (3) root-knot, and (4) aphids. The two dis-
eases which cause the heaviest losses every year are Blight, and
Bacterial Rot of the fruit. In this paper we are only concerned
with the Bacterial Rot of the fruit.
In the spring of 1911, many complaints were received from
cucumber growers in Levy and Alachua counties, that the cu-
cumbers were rotting on their way to market. The cucumbers
left the fields in a seemingly healthy condition, but by the time
they reached the market the baskets would be reported to be
"leaky." Inquiries were sent to the different commission
houses to find out in what condition the cucumbers were arriv-
ing on the market. They replied that the cucumbers from
Levy and Alachua counties were arriving in bad condition.
They described the disease as a small white speck on the cu-
cumbers; and stated that if on further examination the fruit
should be halved, there would be a brown soft area underneath
the spot (Fig 40). This browning seemed to spread, and later
the whole cucumber became a soft watery mass.






Florida Agricultural Experiment Station


CHARACTER OF THE DISEASE

A study of field conditions shows that not only are the ma-
ture cucumbers affected, but also the vines. The disease first
makes its appearance on the leaves as dark watery spots. An
examination of these spots early in the morning reveals the
presence of a watery substance hanging on the underside of the
leaf beneath the spot. Later in the day, this watery substance
evaporates, and there remains a white, chalk-like residue. As
the disease progresses, these spots dry out and become brown;
and then the tissues become brittle and fall away, making a
hole in the leaf. The spots range from one-eighth to a fourth
of an inch in diameter, and frequently become confluent. A
leaf badly affected with the disease has a rather torn and
ragged appearance (Fig. 37). Young plants may become af-
fected. One field was found in which plants with only three or
four leaves were badly affected .

FRUIT INFECTION

The infection makes its appearance on the cucumber fruit
as a small watery spot about one-sixteenth of an inch in diam-
eter. The cuticle becomes ruptured and a gummy liquid ex-
udes. This exudate evaporates and the residue gives the spot


Fig. 38-Natural infection on cucumber. (Twice natural size.)


A I






Florida Agricultural Experiment Station


CHARACTER OF THE DISEASE

A study of field conditions shows that not only are the ma-
ture cucumbers affected, but also the vines. The disease first
makes its appearance on the leaves as dark watery spots. An
examination of these spots early in the morning reveals the
presence of a watery substance hanging on the underside of the
leaf beneath the spot. Later in the day, this watery substance
evaporates, and there remains a white, chalk-like residue. As
the disease progresses, these spots dry out and become brown;
and then the tissues become brittle and fall away, making a
hole in the leaf. The spots range from one-eighth to a fourth
of an inch in diameter, and frequently become confluent. A
leaf badly affected with the disease has a rather torn and
ragged appearance (Fig. 37). Young plants may become af-
fected. One field was found in which plants with only three or
four leaves were badly affected .

FRUIT INFECTION

The infection makes its appearance on the cucumber fruit
as a small watery spot about one-sixteenth of an inch in diam-
eter. The cuticle becomes ruptured and a gummy liquid ex-
udes. This exudate evaporates and the residue gives the spot


Fig. 38-Natural infection on cucumber. (Twice natural size.)


A I






Bulictin 121


Fig. 39-Young cucumbers naturally infected.

a white appearance (Fig 38). Gum masses of an amber color,
a quarter of an inch in diameter have frequently been found.
The infection does not spread laterally on the surface, but goes
towards the center of the cucumber. When the infected re-
gion reaches the vascular system its progress is rapid. In a
few days the interior of the cucumber becomes a soft watery
mass.
Our attention was also called to the fact that the cucum-
ber vines were not setting fruit. A careful examination was
made of several fields, and it was found that the plants were
setting fruit, but many cucumbers of all sizes were found rot-
ting on the vines (Fig. 39). The younger fruits are more sus-
ceptible to infection.
One of the leading characteristics of the disease, as stated
before, is the rotting of the fruit in transit. A carload of cu-



V _" tN. '
r i^ i^a'*_,: ^ a 'V,
vm r*


Fig. 40-The disease working inward.






Florida Agricultural Experiment Station


cumbers that left the field apparently sound, arrived on market
in such bad condition that the sale was not sufficient to pay the
freight. Another grower sent forty-eight baskets of cucum-
bers to the New York market, and received $8.75 in return, the
complaint being that the fruit was soft on its arrival at the
market. Other similar instances might be cited.
It was in 1911 that this disease was first called to our at-
tention. Some of the older growers had received similar com-
plaints from the market eight years ago. They also state that
the trouble seemed worse during wet season or right after con-
tinued rains. The infection seemed to be worse in 1912 than it
was in 1911 or 1913. Records for rainfall were examined to
find out the amount of precipitation for January to June dur-
ing the three years. The total rainfall for the first six months
of 1911 was 11.65 inches; in 1912, 30.14 inches, and in 1913,
21.43 inches. The number of rainy days in the first six months
of 1911 was 30; in 1912, 74, and in 1913, 60. There were only
12 rainy days during April and May in 1911, while in 1912 there
were 17 rainy days during these months. In 1913, the disease
did less damage than in 1911 and 1912. During April and May,
1913, there were only nine rainy days. April and May are the
critical months, when the growing and harvesting of the fruit
take place.
Below is a table comparing the yields of 1911 and 1912.
The data were given in answers to letters sent out for this pur-
pose. The reduction in yield was wholly or largely due to this
bacterial rot.

No. Acres Total Yield No. Acres Total Yield Per cent of
GROWER 1911 (Baskets) 1912 (Baskets) reduction
A ........... 5 1700 5 750 56
B ...........Io 4000 IO 1625 59
C ........... 9 6021 14 3o00 67
D ........... 30 9000 65 7000 64
E ...........Io 5600 o1 2300 59







Bulletin 121


Of the 104 acres represented here for the year 1912, 64
were planted to cucumbers in 1911, and the other 40 acres were
contiguous to the 64.
In 1913 no complaint was received of cucumbers rotting
until the latter part of the season. We had but little rain until
the main crop had been gathered, and then the cucumbers also
become affected with the fungus blight, (Pseudoperonospora
cubensis). After this blight got started in the fields there was
very little picking done.

CAUSE OF THE DISEASE

A microscopical examination was made of the cucumbers
as they were brought into the laboratories. Also some of the
affected tissue was killed in chrom-acetic acid and stained with
methylene blue. The only organisms found that could be sus-
pected of causing the disease were bacteria. These were found
in the intercellular spaces, and also where the middle lamellae
had been dissolved.
The action of the bacteria seems first to swell the cell
walls; then the middle lamellae are dissolved and the cells are
freed from each other; and lastly the whole cucumber is re-
duced to a soft watery mass. Action similar to this was also
noticed by Jones in the "Soft Rot of Carrots," (Vermont Agr.
Expt. Sta., Bul. 147). Giddings reports the same thing in mel-
ons (Vermont Agr. Expt. Sta., Bul. 148).

ISOLATION OF BACTERIA

Cucumbers were taken which showed early stages of spots,
and washed in 95 per cent alcohol. A sterilized scalpel was
then used to halve the cucumber through the infected spot.
Another sterilized scalpel was used and a thin slice shaved off
the affected area. Some of the tissue was then removed with
a sterile needle, and plate cultures on standard agar were made.
In two days small white columns made their appearance. Trans-
fers were then made to agar slants and to beef bouillon. Cul-
tures were also obtained by cutting away the cuticle with a
sterilized scalpel; and then with another sterilized scalpel some


IOI







Florida Agricultural Experiment Station


of the infected tissue was removed and placed in a tube of
standard beef bouillon. Inoculations were afterwards made
from these two kinds of isolations, and the characteristic spot-
ting of the leaves and fruit was produced.

PRELIMINARY TESTS

Before the pure cultures were secured for inoculation, in-
fected leaves were pinned on healthy leaves, and then wrapped
with paraffined paper. In six days the disease appeared on the
healthy leaves. As a check, healthy leaves were pinned to
healthy leaves and then wrapped in paraffined paper; and no
infection occurred.
The surface of a diseased cucumber was sterilized with 95
per cent alcohol, and a piece of the affected tissue removed by
means of a sterile scalpel. The surface of a healthy cucumber
was sterilized in the same manner, and an incision made with
a sterile scalpel. The piece removed from the affected cucum-
ber was then inserted in the healthy cucumber which was
wrapped in paraffined paper. In five days the cucumber was
diseased, and a large drop of gum had collected at the point of
inoculation. A healthy cucumber was treated in the same way,
excepting that the material inserted was taken from a healthy
fruit. No infection resulted.

INOCULATIONS

The bacteria which were growing in standard beef bouillon
were applied to leaves with a camel's hair brush. The char-
acteristic leaf spotting was produced.
Bacteria were applied to cucumber fruit with a camel's hair
brush, and the cucumber was then wrapped in paraffined paper.
The characteristic spotting was produced.
Cucumbers were sterilized with 95 per cent alcohol, and
then pricked with a sterile needle. A pure culture of the bac-
teria was then placed on the wound; in a few days the cucum-
ber gummed as the result of infection (Fig 41). Pure bouillon
cultures were brushed in open flowers. The young ovaries did
not develop but withered and died. These young ovaries were
like the small fruit picked off the vines (Fig 42).





Bulletin 121


Fig. 41-Inoculation of old cucumber after wounding with needle.
(Check on right.)
In 1913 the work was repeated and the results which were
obtained in 1912 were verified. Isolations were made at dif-
ferent times from inoculated cucumbers, and the same organ-
ism was always recovered. Fifty inoculations were made,
forty-two infections resulted. Twenty checks were made and
no disease occurred.







Ii


Fig. 42-Two young cucumbers inoculated. (check on right.)







104 Florida Agricultural Experiment Station

Below is given a table of the number and the times of in-
oculations:

DATE No. of No. of No. of No. of Infec-
Inoculations Infections Checks tions in Checks
April 15, 1913 8 cucumber leaves 8
2 summer squash leaves 2
April 28, 1913 6 cucumbers 6 3 0
May 3, 1913 9 cucumbers 8 6 0
May 13, 1913 7 cucumbers 6
May 15, 1913 7 cucumbers 5 5 0
May 21, 1913 5 cucumbers 6 6 0

After a culture is placed on the cucumber fruit it takes
from five to ten days before infection is visible. If, however,
the fruit is first injured and the culture is placed on the wound,
the infection is apparent in three to five days. If a culture is
placed in the flower, the ovary seems to grow very little if at all
after the inoculation. Two cucumbers were the same size when
one was inoculated. After inoculation this one made no fur-
ther growth, while the check continued to grow.
Summer squash and pumpkin leaves were also inoculated
with pure cultures. Infection became apparent in from three
to five days.

THE BACILLUS

The bacillus which causes this disease is two twenty-five
thousandths of an inch in width. It is actively motile by peri-
trichate flagella. It stains readily with gentian violet. Grown
on agar containing any of the sugars it becomes yellow, with
age. A young agar colony is white. The bacillus was grown
in different media; and, in accordance with the descriptive
chart of the Society of American Bacteriologists, its number is
222.3332113. A description of this bacillus will be found in the
Report of the Florida Experiment Station for 1913, and in
"Phytopathology" for June, 1913.







Bulletin 121


SPRAYING EXPERIMENTS
Spraying experiments were conducted in the fields at Wil-
liston, Fla., for the control of this disease. Bordeaux mixture,
4-6-50 formula, was used. Fifty gallons were applied per acre,
with an Iron Age traction sprayer. The spray nozzles were so
arranged that seven rows were sprayed at a time. Four spray-
ings were made on March II and 22, April II and 17, respect-
ively. They should have been made every ten days but un-
avoidably the spraying for April I was omitted. Before April
ii there was noticed an increase in the disease in the sprayed
plots. To be able to get the best results one must keep the
leaves coated with Bordeaux mixture.
The field was divided into plots and in each plot there was
left one row unsprayed as a check. The cucumbers were picked
from the check row and one of the sprayed rows next to it.
The field used for the experiment was planted early and had
been considerably damaged by the wind storm in March, which
accounts for its small yield. Below is a table giving dates of
four pickings and the amount of fruit diseased on the sprayed
and unsprayed rows, in three plots:


Ist Plot April 2
Sprayed
Healthy fruit .... 44
Infected fruit .... ..
Unsprayed
Healthy fruit .... 56
Infected fruit .... 16
2nd Plot
Sprayed
Healthy fruit .... 51
Infected fruit .... 4
Unsprayed
Healthy fruit .... 74
Infected fruit .. 25
3rd Plot
Sprayed
Healthy fruit .... 89
Infected fruit .... 7
Unsprayed
Healthy fruit .... 81
Infected fruit .... 19


25 April 29 May 12 May 17


I 21
I 15


Total

84
II

86
39


102
24

134
74


142
32

121
74







Florida Agricultural Experiment Station


The above table shows that 17 per cent. of the sprayed
cucumbers were affected and 35 per cent. of the unsprayed.
There were more cucumbers on the unsprayed rows, but they
were smaller; while the sprayed rows produced larger and bet-
ter fruit. The foliage during the whole season was greener
and in better condition on the sprayed rows than on the un-
sprayed.
IRRIGATION

When the disease made its appearance in the spring of
1911 it was first noticed on fields which were irrigated; but
when the rains began it appeared also on fields not irrigated,
indicating that moisture is an essential factor in the spread of
the disease.

NITRATE OF SODA

The use of nitrate of soda to force the cucumbers is a com-
mon practice among growers. It is applied about a week or
ten days before picking commences, and one or two more ap-
plications are generally made during the season. The amount
of nitrate of soda used varies from 50 to 150 pounds per acre.
On account of this quick growth the cucumber is soft and
watery and does not hold up well in transit. It has also been
shown by Spinks in England (Journal of Agricultural Science,
Vol. V, pt. 3) that nitrate of soda makes some plants more sus-
ceptible to disease.
The writer applied nitrate of soda at the rate of Ioo pounds
per acre to cucumbers grown in the greenhouse in 1913; they
were more susceptible to the disease than plants not fertilized
with nitrate of soda in 1912. A grower used different kinds of
fertilizer in four different plots. The plot which was affected
with the disease the worst, had received the fertilizer which
contained the highest percentage of available nitrogen. The
effects of nitrate of soda on cucumbers has not been thoroughly
worked out, but the writer discourages the free use of it to force
the crop.







Florida Agricultural Experiment Station


The above table shows that 17 per cent. of the sprayed
cucumbers were affected and 35 per cent. of the unsprayed.
There were more cucumbers on the unsprayed rows, but they
were smaller; while the sprayed rows produced larger and bet-
ter fruit. The foliage during the whole season was greener
and in better condition on the sprayed rows than on the un-
sprayed.
IRRIGATION

When the disease made its appearance in the spring of
1911 it was first noticed on fields which were irrigated; but
when the rains began it appeared also on fields not irrigated,
indicating that moisture is an essential factor in the spread of
the disease.

NITRATE OF SODA

The use of nitrate of soda to force the cucumbers is a com-
mon practice among growers. It is applied about a week or
ten days before picking commences, and one or two more ap-
plications are generally made during the season. The amount
of nitrate of soda used varies from 50 to 150 pounds per acre.
On account of this quick growth the cucumber is soft and
watery and does not hold up well in transit. It has also been
shown by Spinks in England (Journal of Agricultural Science,
Vol. V, pt. 3) that nitrate of soda makes some plants more sus-
ceptible to disease.
The writer applied nitrate of soda at the rate of Ioo pounds
per acre to cucumbers grown in the greenhouse in 1913; they
were more susceptible to the disease than plants not fertilized
with nitrate of soda in 1912. A grower used different kinds of
fertilizer in four different plots. The plot which was affected
with the disease the worst, had received the fertilizer which
contained the highest percentage of available nitrogen. The
effects of nitrate of soda on cucumbers has not been thoroughly
worked out, but the writer discourages the free use of it to force
the crop.






Bulletin 121


PICKING AND PACKING THE FRUIT

Great care should be exercised in the picking and packing
of the fruit. The fruit should be cut with a sharp knife. Many
times a large piece of the cucumber is broken off at the stem
end when the cucumber is pulled off the vine. This wound
gives a ready entrance for fungi and bacteria which cause de-
cay. In throwing the cucumbers into the baskets they become
bruised and cut when they strike the edges of the wooden
strips. To lessen the danger of injury the picking baskets
should be lined with canvas or burlap. Also injury takes place
in dumping the cucumbers out of the baskets into the bins in
the packing sheds. Care should be taken in constructing the
bin that all rough surfaces are made smooth.
The affected cucumbers should not be packed. Every
cucumber showing a small mark of being affected should be
discarded and thrown away. The affected fruit will rot before
it reaches the market. The soft watery mass will be distrib-
uted over the healthy and wounded cucumbers in the pack and
consequently infection will take place. It has been shown by
inoculation that it only takes three to five days tor a cucumber
to begin rotting, if the bacteria enter a wound. If, however,
there are no wounds, the bacteria cause an infection in from
five to ten days. It takes a car of cucumbers four to eight days
to reach the market; so it can be plainly seen that cucumbers
can become infected in transit and rot before they reach the
market.
An experiment was made in shipping affected fruit. Two
baskets were packed with fruit all showing signs of being in-
fected. They were placed in a car of cucumbers and shipped to
New York market. When the car arrived in the market, these
two baskets were reported to be leaking, and they sold for
fifty cents less than the sound fruit. Every affected cucumber
packed lessens the value of the basket. The affected cucum-
bers should not be left lying about the packing house; neither
should they be thrown on a pile in the field. They should
be carted off and buried in the woods, or in a field which will
not be planted to cucumbers.






Florida Agricultural Experiment Station


CONTROL

While the spraying experiments should be carried on for
several years, and different spray solutions tried; the results
obtained from these experiments indicate that spraying with
Bordeaux mixture is in a measure a control. Spraying should
begin while the plants are young, when they have only three or
four leaves, and be repeated every ten days. The spraying
must be done thoroughly or it will be of little benefit. A good
force pump should be used, one which will apply not less than
fifty gallons of the spray mixture per acre. There must be
power enough in the pump to form a mist of the spray when
it is delivered by the nozzle. It will require from eighty to a
hundred pounds pressure to do good work.

BORDEAUX MIXTURE

Bordeaux mixture is made from bluestone, rock lime, and
water. It is useful for treating fungus diseases of plants, but
should not be used against insects.
If one has much spraying to do, it is better to make stock
solutions of the bluestone and lime; from these, Bordeaux mix-
ture of any strength can be made. Take a barrel which holds
fifty gallons of water: suspend fifty pounds of bluestone in a
gunny or cheese cloth sack at the top of the water; let half of
the bluestone be below water. After it is all dissolved, there
will be one pound of bluestone to every gallon of the solution.
In another barrel take fifty pounds of good rock lime and
slake it. After it is slaked, add water until there are fifty gal-
lons of the limewater.
Bordeaux mixture is used in different strengths, according
to the kind of plants to be sprayed, and the time of the year.
A 5-5-50 Bordeaux mixture means a mixture containing
five pounds of bluestone, five pounds of lime and fifty gallons
of water. In all formulae of Bordeaux mixture, the first figure
refers to the number of pounds of bluestone, the second figure
to the number of pounds of lime, and the third to the number
of gallons of water.
Preparing the Mixture.-Two more barrels of fifty gallons
capacity are needed. In one barrel put forty gallons of water
and ten gallons of the bluestone solution. In the second barrel






Bulletin 12r 109

put forty gallons of water and ten gallons of the lime water.
Take equal parts from each of the two barrels containing the
dilute solution, and pour them simultaneously into a spray ma-
chine. The solution should be kept agitated while the mixing
is taking place. The lime solution should be kept stirred so
that each gallon will contain the same amount of lime.
Only wooden or copper vessels should be used, as blue-
stone corrodes other metals. Be sure and pour the mixture
through a fine sieve or cheese cloth before putting it into the
sprayer, or the particles will clog the nozzles.
Bordeaux mixture must be used the same day that it is
made; for if left standing over night, it loses its strength. The
stock solutions of bluestone and lime can be kept indefinitely,
but care must be taken that when they are to be used the water
which has evaporated in the meantime is replaced.




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