• TABLE OF CONTENTS
HIDE
 Front Cover
 Front Matter
 Soils
 Preparation of the soil
 Fertilization
 Planting
 Seed potatoes
 Cultivation and harvesting
 Marketing, rotation, and irrig...
 Frost protection
 Diseases














Group Title: Bulletin - University of Florida Agricultural Extension Division ; 36
Title: Irish potatoes in Florida
CITATION PAGE IMAGE ZOOMABLE
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Permanent Link: http://ufdc.ufl.edu/UF00025536/00001
 Material Information
Title: Irish potatoes in Florida
Series Title: Bulletin
Physical Description: 16 p. : ill. ; 23 cm.
Language: English
Creator: Spencer, A. P ( Arthur Perceval )
Publisher: Agricultural Extension Division, University of Florida
Place of Publication: Gainesville Fla
Publication Date: 1923
 Subjects
Subject: Potatoes -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by A.P. Spencer.
General Note: "June, 1923".
Funding: Bulletin (University of Florida. Agricultural Extension Division) ;
 Record Information
Bibliographic ID: UF00025536
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 002570130
oclc - 47285731
notis - AMT6437
 Related Items
Other version: Alternate version (PALMM)
PALMM Version

Table of Contents
    Front Cover
        Page 1
    Front Matter
        Page 2
    Soils
        Page 3
    Preparation of the soil
        Page 4
    Fertilization
        Page 5
        Page 6
    Planting
        Page 7
    Seed potatoes
        Page 8
        Page 9
    Cultivation and harvesting
        Page 10
        Page 11
    Marketing, rotation, and irrigation
        Page 12
    Frost protection
        Page 13
    Diseases
        Page 14
        Page 15
        Page 16
Full Text



Bulletin 36


June, 1923


COOPERATIVE EXTENSION WORK IN
AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914) iL 14
AGRICULTURAL EXTENSION DIVISION, UNIVERSITY OF FLOIDA,
AND UNITED STATES DEPARTMENT OF AGRICULTURE, .... .:
COOPERATING
WILMON NEWELL, Director





IRISH POTATOES IN FLORIDA
By A. P. SPENCER


01


Fig. 1.-Potato grading machine at work


Bulletins will


be sent free upon application to the Agricultural Extension
Division, Gainesville, Florida










BOARD OF CONTROL


P. K. YONGE, Chairman, Pensacola
E. L. WARTMANN, Citra
J. B. SUTTON, Tampa
JOHN C. COOPER, Jacksonville
W. L. WEAVER, Perry
J. T. DIAMOND, Secretary, Tallahassee


STAFF, AGRICULTURAL EXTENSION DIVISION
A. A. MURPHREE, A.M., LL.D., President of the University
WILMON NEWELL, D.Sc., Director
A. P. SPENCER, M.S., Vice-Director and County Agent Leader
RUBY NEWHALL, Secretary
RALPH STOUTAMIRE, B.S.A., Editor


COOPERATIVE AGRICULTURAL DEMONSTRATION WORK
E. W. JENKINS, B.Ped., District Agent
H. G. CLAYTON, M.S.A., District Agent
S. W. HIATT, District Agent
R. W. BLACKLOCK, A.B., Boys' Club Agent
JOHN M. SCOTT, B.S., Animal Industrialist
N. W.'SANBORN, M.D., Poultry Husbandman
HAMLIN L. BROWN, M.S., Dairy Specialist
ED L. AYERS, B.S., Entomologist and Plant Pathologist


COOPERATIVE HOME DEMONSTRATION WORK
SARAH W. PARTRIDGE, State Home Demonstration Agent
HARRIETTE B. LAYTON, Assistant State Home Demonstration
Agent
AGNES I. WEBSTER, B.S., District Agent
ELLEN LENOIR, B.A., District Agent
MAY MORSE, R.N., Extension Home Dairy Agent
MINNIE M. FLOYD, B.S., Extension Farm Poultry Agent
MADGE HORN, Assistant Clothing Agent








IRISH POTATOES IN FLORIDA
By A. P. SPENCER

Irish potatoes are grown both as a truck crop and as a farm
crop in Florida. In sections where the largest acreage is planted
most of the area of the farms is planted to potatoes. While this
crop has been grown in Florida for forty years or more, until
recently it was not considered an important crop except in very
limited areas and then only on soils particularly suited to it.

SOILS
Unquestionably, some soils are better adapted to this crop than
others, nevertheless it is certain that Irish potatoes can be grown
in nearly every part of Florida and on many soils that were for-
merly considered unsuitable. Soils well-filled with humus and
which have ample moisture and proper drainage are preferred.
The Irish potato growing sections of Florida are chiefly on
flatwood soils. Much of this land is underlaid at varying depths
with a compact formation of clay, marl or hardpan. Where this
formation lies close to the surface, it is advisable to break it up
by deep plowing or by subsoiling. If the hardpan is four feet
or more below the surface, it is advantageous in that it may
prevent the rapid escape of irrigation waters.
Many of these soils have little humus when first broken, but
by the proper rotation of crops large amounts of vegetable mat-
ter may be turned under each year. This increases the humus
content, until a first-class, potato-growing soil results. It is
important that flat lands have good drainage.
Decomposed and well-settled muck land produces satisfactory
yields of Irish potatoes with little or no commercial fertilizer;
but, on account of a greater tendency to cold injury on muck
lands, they are not satisfactory for a winter crop, except in
protected places in South Florida.
Hammock land, if well-drained, is good for Irish potatoes, be-
cause of the amount of humus it contains and its ability to hold
moisture.
High sandy lands are less suitable for Irish potatoes than are
flatwood or hammock lands. This is because of their lack of
humus, their open sandy character, and their consequent lack of
moisture during the growing season. When high pine lands can
be supplied with humus and be irrigated, they can be made to







Florida Cooperative Extension


produce profitable crops of Irish potatoes, especially if underlaid
with clay.
Scrub-oak or pine lands are not suitable for growing Irish po-
tatoes, because of their dry sandy character, their lack of humus,
and the small amount of plant food they naturally contain.

PREPARATION OF THE SOIL
Besides being fertile, Irish potato land should be kept well
cultivated so that it will hold moisture and retain soluble ferti-
lizers. The crop must grow rapidly and have a ready supply of
plant food. Otherwise the tubers will be small and unmarketable.
The soil should be plowed broadcast, six to ten inches deep,
turning under all vegetable matter two months before planting,
then disked two or three times until the vegetation is thoroly
mixed with the soil, then smoothed with a heavy harrow every
ten days until time to plant.
Where the ridges from the previous year's crop have not been
levelled down and there is not a heavy growth of weeds or grass
to plow under, the land can be thoroly prepared by splitting the
old ridges with a plow or middle buster, thereby making the ridge
where there was a furrow the previous year. The ridges are


Fig. 2.-Florida potato field. Note high ridges and beds with water furrows
between







Irish Potatoes in Florida


then shaped up and finished by the use of a disk cultivator. This
method requires less labor than plowing broadcast and is gen-
erally practiced by successful potato growers when the soil is in
good cultural condition.
On flat land where water is likely to stand after rains, the
fields should be plowed up into 20- to 30-foot beds by beginning
at the center of the bed and plowing each furrow toward the cen-
ter. If the land is very flat, a second plowing in this way may be
necessary to raise the bed high enough. Disk the soil to the cen-
ter of the bed, so that by planting time there will be a water
furrow between the beds 18 inches lower than the centers. This
dead furrow, connected with an open ditch, lowers the water
table and provides good drainage against ordinary rains and pre-
vents flooding the land in case of excessive rainfall.
If the land is sloping and has natural drainage, the furrows
should be run in the direction which facilitates drainage. On
such lands bedding is unnecessary and the cost of preparation
and cultivation will be less.
New land seldom produces a profitable crop the first year, and
it is advisable to plant to velvet beans or a forage crop at least
one year, or longer if necessary, until the soil becomes sufficiently
fertile to grow any crop that requires expensive culture.

FERTILIZATION
Irish potatoes require a complete fertilizer on most soils; this
should be modified according to the variation of soils.
On flatwood lands a fertilizer analyzing 3 to 5 percent am-
monia, 6 percent phosphoric acid and 5 to 6 percent 'potash has
given excellent results. A ton of such fertilizer may be made
from either of the following formulas:
1. 110 lbs. nitrate of soda
800 lbs. cottonseed meal (71/2 percent ammonia)
750 lbs. acid phosphate (16 percent)
252 lbs. sulphate of potash (48 percent)
88 lbs. filler.
2. 500 lbs. blood and bone (16 percent)
750 lbs. acid phosphate (16 percent)
252 lbs. sulphate of potash (48 percent)
498 lbs. filler.
There is usually no advantage in adding the filler, as it con-
tains no plant food. However, with some mixtures it makes dis-
tribution of the fertilizer easier because of its better mechanical






Florida Cooperative Extension


condition. If the filler is omitted, there will be less weight and
material to haul and distribute, and the amount applied to the
acre should be proportionately less.
Such a fertilizer is also suitable for average hammock land,
but on dark-colored hammock land having large amounts of de-
caying vegetable matter the ammonia may be reduced to 2 per-
cent. On high pine land which is lacking in humus the ammonia
may be increased to 5 percent and should be supplied from an
organic source.
In applying fertilizer one must also consider the cost of the
mixture. Should any of the above-mentioned materials be un-
usually expensive, it is usually economical to substitute with
some other material that can be purchased at a lower unit cost,
even tho the yield may be slightly reduced. However, the largest
amount of ammonia should come from organic sources. The
phosphate should be from quickly available materials, especially
that for the winter crop which usually sells for the highest prices,
being the earliest crop marketed. The amount of fertilizer to
apply depends upon the condition of the soil. Where the soil has a
large supply of humus and is in good physical condition, from
1500 to 2500 pounds to the acre may be applied economically.
But on newer lands where the depth of the soil is less than eight
inches, from 1200 to 1500 pounds is the maximum amount that
can be used profitably. The addition of five tons of well-rotted
stable manure to each acre, or of a compost made from muck
soil, oak leaves and decayed grasses, applied 30 days before plant-
ing, produces a healthy growth of the plant with a beneficial
effect on the yield of potatoes.
The fertilizer is applied either in one or two applications.
One application before planting is preferred to two or more on
well-prepared land that has a fair supply of humus. This may
be either broadcasted and disked into the soil or drilled in by
opening the center of the ridge, then drilling the fertilizer into
the opened ridge with a fertilizer distributor and afterward
shaping up the bed with a disk cultivator. This should be done
ten days or more before the seed are planted.
Two applications are recommended on thin sandy soils lacking
in humus or in cases where heavy rains have leached out a good
portion of the first application. The second application should be
drilled into the sides of the ridges.
When quantities of crab grass, beggarweed and other vegeta-
tion are turned under, thus supplying the soil with humus, com-






Irish Potatoes in Florida


mercial fertilizer is more beneficial, due to the increased bac-
terial action induced by the added humus. Soils lacking in humus
seldom produce an average yield even when heavy applications
of commercial fertilizer are made.

PLANTING
On flat land, Irish potato rows should be ridged 12 to 16 inches
high, or sufficiently high to give proper drainage. On well-drained
land the cultivation may be almost flat, altho most growers pre-
fer to plant the seed on ridges. The rows may be three and one-
half feet apart with one seed dropped in the rows every 12 to 16
inches. The seed should be covered about three inches deep. If
the land is not in the best state of cultivation it will be better to
have the rows four feet apart.
Winter Planting.-The greatest acreage of Irish potatoes in
Florida is winter-planted and the crop is sold on northern mar-
kets. From Tampa southward, planting should be done between
December 15 and January 15. In Middle and North Florida
planting should be done between January 1 and March 1. In some
parts of the state, on account of the probability of frost injury,
late planting is advisable, if for home use. In order to sell for
high prices in northern markets, the new crop must be large
enough to ship, be planted early, fertilized well and cultivated


Fig. 3.-A machine potato planter







Florida Cooperative Extension


thoroly. On lands well protected against freezes planting may
be two weeks earlier. The plants will stand a light frost but not
a freezing temperature, so it is well to avoid planting too early
for the spring crop in North Florida because of the freezing
temperature that may occur up to March 1. If the vines are well
grown but still immature, a freeze may destroy the crop; but,
if they are just putting out their first leaves and getting most
of their nourishment from the tuber, they will sprout up again
and the injury will be slight. Under favorable conditions about
90 days are required after planting for the tubers to attain a
marketable size. Usually 100 days or more is the time necessary
for the production of good quality potatoes.
Fall Planting.-The fall-planted Irish, potato crop is seldom
shipped to distant markets. There is usually, however, a good
demand for it on local markets and at a fair price. Therefore,
if one has a soil suitable for a fall crop, it is advisable to grow
it in order to supply the home market; and this is the only market
it is profitable to grow such potatoes for.
In Central and West Florida, planting should be done not later
than September 1, and in South Florida by September 15. This
will permit digging the crop by Christmas, after which the land
may be planted to winter vegetables.
The method of preparing and fertilizing the soil is the same
as for winter planting, althq there is less need for high ridges
and beds for drainage. The rows, however, should not be less
than four feet apart, and the seed dropped 16 inches apart in
the rows. The probability of less moisture in the soil in the fall,
because of the higher average temperature during September
and October than during the growing season of the winter crop,
makes it advisable to place the rows of fall plantings farther
apart. Furthermore, soils that are naturally dry are less suitable
for fall than for winter planting.
In South Florida a considerable acreage is planted in October
to produce new potatoes for mid-winter markets. The plantings
are treated about like the fall crops.

SEED POTATOES
As only a few varieties have proved satisfactory for Florida
planting, growers should exercise special care to get seed that
is true to type in both color and shape. Tubers that show con-
siderable variation from this may be mixed varieties or may be
from diseased fields,. -Some of the most destructive diseases are






Irish Potatoes in Florida


carried in the field, so that only seed from inspected fields should
be planted, and even with this precaution the seed should be
treated also. It is never advisable to plant potatoes usually sold
by grocers for table use, as they may be diseased and not of the
proper variety. Florida-grown seed potatoes are not generally
used for winter planting as the spring-grown crop must be kept
too long and the fall crop does not mature sufficiently well to
give reliable seed. Most of the seed used in Florida is grown in
eastern states, principally Maine. For fall planting, the seed may



















Fig. 4.-Spaulding's Rose 4 is the favorite variety for
winter planting

be taken from the spring-grown Florida crop. The potatoes should
be kept over summer spread out in a dry place. By planting
only sprouted tubers a fair stand will result.
The most successful growers prefer medium-sized tubers for
seed, and cut them to two well-matured eyes in each piece. Where
the seed potatoes are of average size and are to be planted in three
and one-half foot rows, about five bags weighing 165 pounds
each will be required to plant an acre. It is best to cut the seed
immediately before planting. If any cut seed must be kept a week
or longer, a small amount of lime mixed thru the pile has a pre-
serving effect on the cut surfaces.
Varieties.-The varieties that have given best results in Flor-
ida are: Spaulding's Rose 4, Bliss Triumph, and Irish Cobbler.








Florida Cooperative Extension


Spaulding's Rose 4 is the favorite for winter planting. It is a
smooth potato, grows rapidly, matures early and is a good ship-
per. Bliss Triumph is equally satisfactory for fall planting.

CAUSES OF IMPERFECT STANDS
An imperfect stand may be due to planting immature or dis-
eased seed, to too deep planting on soils with poor drainage, to
too shallow planting where there is insufficient moisture, or to
planting on new land that has not been thoroly prepared. Where
a stand is imperfect, it is impossible to get the maximum yield
even tho all other conditions may be best. Unfavorable condi-
tions must be avoided to make Irish potato growing profitable
in Florida under the expensive cultural methods usually prac-
ticed.

CULTIVATION
Irish potatoes require frequent cultivation as soon as the dan-
ger from injury by cold is past. Frequent cultivation is most
important to conserve soil moisture. When the rainfall is plen-
tiful, especially on soils that have a tendency to become com-
pact, frequent cultivation is necessary to keep the soil in a loose
condition and to hasten the growth of the plants. Grass or weeds
growing in the rows take both moisture and fertilizer, and must
be kept down. When the first plants are beginning to break the
surface, it is advisable to cultivate the top of the ridges with
a board drag, thereby breaking the hard crust that usually forms
and giving light cultivation at the same time.
The disc cultivator is perhaps the most satisfactory imple-
ment for cultivating Irish potatoes grown on high ridges. With
the inner discs set higher than the outer ones, the bottoms and
sides of the beds can be properly cultivated.
A V-shaped cultivator that will stir the bottoms of the fur-
rows and sides of the banks does good work; Where the ridges
are low cultivation can be done with an ordinary cultivator which
will pull down the dirt from the ridges. This dirt can be thrown
back again with a plow.

HARVESTING
For marketing, it is not necessary that the Irish potato be
thoroly ripened. When the crop has reached a marketable size,
and the skin slips on pressure of the thumb, the potatoes are






Irish Potatoes in Florida


ready to dig. When the tubers are to be used for seed, they
should be allowed to remain in the ground until the tops are
about mature. If the crop has had no setbacks, it should be ready
to dig at from 80 to 90 days after planting. The tops usually die
down in about 120 days and the growth of the tuber stops. Where
several acres are to be harvested, it will pay to use a potato


Fig. 5.-The Bliss Triumph is a satisfactory variety for fall
planting


digger. In small areas they may be dug more cheaply with hand
tools. The potatoes are gathered in slatted crates in the field,
then hauled to the sizer for packing.
The potatoes are graded according to size by a grading ma-
chine or sizer. They are separated into Grade No. 1, Grade No. 2,
and Grade No. 3.
In loading into cars the crates may be set on end or loaded
on the bulge. If set on end, slats should be placed between them;
and when loaded on the bulge, headliners should be used to pre-
vent the barrel heads from being forced out while in transit.






Florida Cooperative Extension


MARKETING

Seventy-five barrels to the acre is a heavy yield. The average
yield should be about forty barrels to the acre.
The usual shipping season is during April and May, when
there is a good demand for new potatoes in northern markets.














Fig. 6.-Grades of potatoes barreled for shipping. From the reader's right,
Grade No. 1, Grade No. 2, Grade No. 3

Florida potatoes reaching distant markets later than this usually
bring a much lower price; hence, the advantage of marketing as
early as possible.
ROTATION
In all sections of Florida, Irish potatoes can be used in a
crop-rotation system. In the largest potato-growing areas it is
a common practice to plant corn after potatoes. The corn may
be planted close to the potato rows before digging; if dug with
hand tools, the digging of the potatoes cultivates the corn. When
the corn is about mature, cowpeas are planted between the rows,
making a third crop on the land. Where cowpeas are not grown,
the land usually grows up in native grasses, which are cut off
for hay or turned under to form humus. Such a rotation gives a
variety of crops and keeps the land in good physical condition.
By such a system the land may grow satisfactory Irish potato
crops several years in succession without detriment to the soil.

IRRIGATION
As Irish potatoes grow best in a well-drained, yet sufficiently
moist soil, irrigation will go a long way toward insuring a nor-







Irish Potatoes in Florida


mal yield when the rainfall is only average or below the average.
When rains are frequent and the soil is deeply prepared and in
good physical condition, irrigation may not be necessary on low
hammock or flatwood land. On high hammock, rolling pine land,
or even in drained-out muck ponds or lake bottoms, irrigation is
usually necessary for good yields. In unusually dry seasons low
yields are to be expected on nearly all Florida soils, unless there
is some artificial method of supplying water to the crop; the
tubers will stop growing unless they have sufficient moisture.
In the artesian-well areas of Florida where the land is level,
surface irrigation from flowing wells can be practiced economi-
cally. When the water must be pumped into a reservoir and
then piped into the field, the cost is so great that the advisability
of installing such a system for Irish potato growing alone is
questionable.

FROST PROTECTION
Since Irish potatoes give best yields when planted on moist
land, there is danger of injury by cold to the winter-planted
crop. A frost will not cause serious injury, but when the tem-
perature ranges between 26 and 32 degrees F., the crop is us-
ually injured. Some of the injury may be prevented and per-
haps overcome by adopting proper cultural methods.
Lands that have a heavy crop of vegetation'should be plowed
deeply as early as October, so that all vegetable matter will de-
cay and become thoroly incorporated with the soil before plant-
ing.
Thoro soil preparation before planting is also good frost pre-
vention because the crop will not necessarily have to be culti-
vated for some time after the seed is planted. In fields where
part of the crop has been cultivated, there is usually a marked
difference in the cold injury; therefore, give as little cultiva-
tion as possible until after the danger from freezing is past.
Avoid cultivation, if weather reports indicate a freezing tem-
perature within 48 hours.
Injury from cold may also be prevented by filling the furrows
with water or by permitting overhead irrigation water to flow
during a freezing period. Small plants may be protected by cov-
ering them with a light furrow. The plants will grow up thru
the covering and no injury will result.
If plants are frozen when quite young, new growth comes im-







Florida Cooperative Extension


mediately from the tuber and there is little injury, but if the top
has made a growth of five or six inches and is frozen back, most
of the new growth that may come starts out from the stalk be-
low the frozen part. When the crop has been seriously injured,
every effort should be made to induce quick growth. If the soil
is dry, it is advisable to irrigate. Cultivation, too, will stimulate
growth and is beneficial. Applications of fertilizer at this stage,
however, are of little benefit. If the injury is followed by dry-
ing winds and poor conditions for growth, it is very likely that
the crop will be cut short.


DISEASES
Late Blight.-Late blight is caused by a fungus, Phytophthora
infestans, which attacks both tops (stems and leaves) and
tubers. The edges or tips of the leaves are usually attacked first.
In the early stages of the disease it appears on the leaves in the
form of water-soaked spots which later become dry and are
brown or almost black in appearance.
During moist and cool weather conditions a downy, whitish
growth is distinctly visible on the under sides of the leaves. This
growth consists of innumerable spores and spore-bearing parts
of the fungus. These spores are scattered by the wind, rain or
implements used in cultivating and fall upon the leaves where
they soon germinate and produce the disease. In a few days the
whole field looks as if the plants had been scorched by fire.
These same spores are also responsible for the rotting of the
tubers. The spores are washed from the tip down along the
stem and into the ground where they infect the tubers, chang-
ing the color of the flesh of the potato to a dirty brown. If dry
weather follows, "dry rot" results; but if the soil remains moist,
a soft rot may develop in which case the tubers will decay rap-
idly.
Methods of Control.-1. If possible, secure seed from a re-
liable dealer who will guarantee them to be free from disease.
2. In selecting seed for planting, discard all potatoes show-
ing signs of decay.
3. The disease can be kept in check by spraying the plants
thoroly with bordeaux mixture (5-5-50 formula). Spraying
should begin when the plants are from four to six inches high







Irish Potatoes in Florida


and be repeated every second week until about ten days before
digging.
Early Blight. -This disease is caused by a fungus known
as Alternaria solani. Both early and late blights are often found
on a single plant and sometimes upon the same leaf.
The disease appears only on the tops; the tubers are not at-
tacked. The diseased areas are small and almost circular in
outline, tho frequently the spots run together, in which case the

















Fig. 7.-A power sprayer is necessary in applying bordeaux mixture for
the control of diseases

circular outline may almost disappear. The diseased areas often
show concentric rings, a peculiarity not found with late blight.
Club-shaped spores are produced upon these brown areas. By
means of these the disease is spread.
The fungus is carried over from one season to another on
parts of the diseased plants. It attacks the tomato and a number
of allied plants as well.
Methods of Control.-Spray with bordeaux mixture as for
late blight.
Bacterial Blight. -The bacterial blight of the potato is
caused by Bacillus solanacearum. It also attacks the tomato,
eggplant and some other solanaceous plants, and frequently does
considerable damage in this state.
The disease is characterized by the wilting of a part or the
whole of the plant. A single leaf or stem may wilt or, if the








Florida Cooperative Extension


main stem be the point first attacked, the whole plant may droop.
Following this wilted condition the plant soon dries up and loses
its foliage.
The disease is caused by bacteria which live in the inner tis-
sues of the plant. If the stem of a diseased plant be cut thru, a
dark layer of tissue just underneath the bark can be seen.
The germs make their way downward thru the stems to the
tubers. On cutting a diseased tuber, a part or all of the fibrous
tissue will show a dusky color. If a cut tuber be squeezed or the
surface exposed, a creamy substance will come out of the dis-
eased spots. This substance contains almost pure cultures of
the bacterium which causes the disease.
The disease is spread largely by grasshoppers, leaf-hoppers
and sucking insects, which carry the disease to healthy plants.
Methods of Control.-1. Plant seed potatoes that are certi-
fied as "disease-free."
2. Rotation of crops should be practiced, avoiding crops sub-
ject to the disease.
3. Wilted plants should be taken out and destroyed.
4. Destroy insects, especially aphis.
The disease seems most prevalent on rolling dry lands; so by
keeping the soil moist the injury is less serious.
Scab.-This disease is easily recognized by the rough, scabby
spots on the potato. It is usually introduced by planting scab-
infected seed, which infects the soil permanently.
The organism causing this disease grows readily in an alka-
line soil, but does not thrive in an acid one, consequently an ap-
plication of lime, or wood ashes, which makes the soil neutral
or alkaline, favors the development of this disease. Fresh stable
manure, applied just before planting, frequently causes scabby
potatoes.
Formulas for Treating Seed.-
1. Formaldehyde, 1 pint; water, 30 gallons. Soak the seed
for two hours in this solution before slicing to plant.
2. Corrosive sublimate, 1 ounce; water, 8 gallons. Soak the
seed for an hour and a half in this solution before slicing to
plant.




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