Front Cover
 Fig. 7 and 8

Group Title: Bulletin - University of Florida Agricultural Experiment Station ; 133
Title: Irish potatoes in Florida
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00026696/00001
 Material Information
Title: Irish potatoes in Florida
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: p. 21-32 : ill. ; 23 cm.
Language: English
Creator: Spencer, A. P ( Arthur Perceval )
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1917
Subject: Potatoes -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: A.P. Spencer.
General Note: Cover title.
General Note: "A revision of Bulletin 120"--T.p.
 Record Information
Bibliographic ID: UF00026696
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000922750
oclc - 18161667
notis - AEN3259

Table of Contents
    Front Cover
        Front Cover
    Fig. 7 and 8
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
Full Text

Bulletin 133 (a revision of Bulletin 120)


Agricultural Experiment Station



Fig. 6.-Showing high ridges and beds with water furrows between the beds

"\ /

The Station Bulletins will be sent free upon application to the Experiment
Station, Gainesville.

February, 1917


Fig. 7.-Bliss Triumph

Fig. 8.-Spaulding's Rose 4


Irish potatoes are grown both as a truck crop and a farm
crop in Florida. In sections where the largest acreage is grown
almost the entire farm is planted in this crop and the undivided
attention of the farmer is given to it until it is marketed. While
this crop has been grown in Florida for forty years or more,
until recently it has not been considered an important crop
except in very limited areas and then only on soils best suited
to it. 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 formerly considered unsuitable.
Irish potatoes grow best in soils well-filled with humus
where there is ample moisture, proper drainage and the sur-
face water can be controlled.
The Irish potato growing sections of Florida are chiefly
on flatwoods soils. Much of this land is underlaid with hard-
pan at varying depths. Where this hardpan lies close to the
surface it is advisable to break it up by subsoiling, or by the
use of dynamite; but when it lies from three and a half to five
feet below the surface, it becomes an advantage by preventing
irrigation water from draining away.
Many of these soils have little humus when first broken,
but by the proper rotation of crops, large amounts of vegetable
matter may be turned under each year. This rapidly increases
the humus content, until a first-class potato-growing soil results.
It is important that flat lands have good drainage.
Hammock lands, if well drained, have good soil for Irish
potatoes, because of the amount of humus they contain and
their ability to hold moisture.
High sandy lands are less suitable for Irish potatoes than
the flatwoods or hammock, because of the lack of humus, their
open sandy character, and the consequent lack of moisture dur-
ing the growing season. When high pinelands can be supplied
with humus and be irrigated, they can be made to produce
profitable crops of Irish potatoes; especially if underlaid with

Bulletin 133, Irish Potatoes

Scrub oak lands are not suitable for growing Irish pota-
toes, because of their dry sandy character, lack of humus, and
the' small amount of plant food they naturally contain.

Irish potatoes require a rich well-cultivated soil that will
conserve moisture and retain soluble fertilizers. The crop must
grow rapidly and must have a ready supply of plant food, other-
wise the tubers will be small and unmarketable.
The soil should be plowed broadcast six to ten inches deep
and all vegetable matter turned under two months before
planting, then disked two or three times until the vegetation is
thoroughly mixed through the soil, then smoothed with a heavy
harrow every ten days until time to plant.
On flat lands where water is likely to stand after rains, the
fields should be plowed up in 16- to 20-foot beds, by beginning
at the center of the bed and plowing each furrow toward the
center. 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 center of the bed, so that by planting time there will be
a water furrow between the beds eighteen inches lower than
the centers. This dead furrow connected with an open ditch
lowers the water table and provides good drainage against ordi-
nary rains and prevents flooding the land in case of excessive
If the land is sloping and has natural drainage the furrows
should be run in the direction to give ready drainage. On such
lands bedding is unnecessary and the cost of preparation and
cultivation will be less.
New lands that have never been cultivated seldom produce
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 has become sufficiently productive to
grow Irish potatoes or any other crops that require expensive
Irish potatoes require a complete fertilizer on most soils;
this should be modified according to the variation of soils.
On flatwoods lands a fertilizer analyzing 4 percent am-
monia, 7 percent phosphoric acid and 71/2 percent potash has
given excellent results. A ton of such fertilizer may be made
with either:

Florida Agricultural Experiment Station

1055 lbs. cottonseed meal, 7% percent ammonia
655 lbs. 16 percent acid phosphate
290 lbs. sulphate of potash, 48 percent potash
800 lbs. blood and bone, 10 percent ammonia
900 lbs. 16 percent acid phosphate
300 lbs. sulphate of potash, 48 percent potash
This mixture is also suitable for average hammock lands,
but on dark colored hammock lands having large amounts of
decaying vegetable matter the ammonia may be reduced to two
percent. On higher pinelands lacking in humus the ammonia
may be increased to five percent and should be supplied from
an organic source.
In applying fertilizer one must also consider the cost of
the mixture. Under abnormal conditions, where it is difficult
to secure potash or when the price is prohibitive, it is advisable
to reduce this element to two or three percent. Where lands
are already in a high state of cultivation it may be more prof-
itable to omit potash entirely, even with a probability of re-
duced yields. While no other element can be substituted for
potash in a fertilizer, the addition of five tons of well-rotted
stable manure for each acre, or of a compost made from muck
soil, oak leaves and decayed grasses, applied thirty days before
planting, produces a healthy growth of the plant with a benefi-
cial effect on the yield of potatoes. The amount to be applied
will depend upon the condition of the soil. Where the soil has
a large supply of humus and is in good physical condition, 1500
to 2000 pounds to the acre may be economically applied; but
on newer lands, where the depth of the soil is less than eight
inches, from 1200 to 1500 pounds will be about the maximum
amount that can be used profitably.
The fertilizer is applied either in one or two applications.
One application before planting is preferable to two or more on
well-prepared lands that have a fair supply of humus. This
may be either broadcasted and disked into the soil or scattered
in the row and covered lightly, making a bed in which the seed
is planted.
Two applications are recommended on thin sandy soils
lacking in humus or in case a heavy rain has leached out a
good portion of the first application. The second application
should be drilled into the sides of the ridges, or if the crop is
planted level it can be broadcasted between the rows and cov-
ered lightly about thirty days after the plants appear above the

Bulletin 133, Irish Potatoes

When quantities of crab grass, beggarweed, and other
vegetation can be turned under, supplying the soil with humus,
the commercial fertilizer is more beneficial to the crop, due to
the increased bacterial action induced by the added humus.
Soils lacking in humus seldom produce an average yield even
with heavy applications of commercial fertilizer.
On flat land, the seed-beds should be ridged 12 to 16 inches
high, or sufficiently to give drainage to the beds. On land well
drained the cultivation may be almost flat, although most grow-
ers prefer to plant the seed on low ridges. The rows may be
made three feet apart, and one seed dropped every 15 or 18
inches. The seed should be covered three to four inches deep.
If the land is not in the best state of cultivation it will be better
to have the rows four feet apart.
The greatest acreage of Irish potatoes in Florida is winter
planted and sold in Northern markets. From Tampa south-
ward, planting should be done between December 15 and Jan-
uary 15; between Gainesville and Tampa, from January 1 to
February 20; and in sections north and west of Gainesville
from February 1 to March 10. On lands well protected against
freezes planting may be fifteen days earlier in each section.
The plants will stand a light frost but not a freezing tempera-
ture, so that it is well to avoid too early planting for the spring
crop in the northern parts of 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 eighty days are required after planting to mature the
tuber to a marketable size.
The fall-planted Irish potato crop is seldom shipped to dis-
tant markets. There is usually, however, a good demand at a
fair price in local markets; so that if one has a soil suitable for
a fall crop it is advisable to grow them to supply the home
In central and west Florida, planting should be done not
later than September 1, and in southern Florida by September

Florida Agricultural Experiment Station

Fig. 9.Planting
15. This will permit digging the crop by Christmas, when the
land may be planted to winter vegetables.
The method of preparing and fertilizing the soil is the
same as for winter planting. The rows, however, should not be
less than four feet apart, and the seed dropped eighteen to
twenty inches in the rows. The probability of less moisture in
the soil during the fall, because of the higher average temper-
ature during September and October than during the growing
season of the winter crop, makes it necessary to give fall plant-
ings more distance in the rows. Furthermore, soils that are
naturally dry are less suitable for fall planting than for winter
In south Florida a considerable acreage is planted in Octo-
ber to produce new potatoes for midwinter markets. The
plantings are treated about like those intended for a fall crop.
Growers should exercise special care to get well-matured
seed from reliable growers or seedsmen who will guarantee

Bulletin 133, Irish Potatoes

them to be true to name and grown in fields practically free
from disease. It is never advisable to plant potatoes usually
sold by grocers for table use as they may be diseased, and not
the proper variety. Florida-grown seed potatoes are not gen-
erally used for winter planting as the spring-grown crop must
be kept too long and the fall crop does not mature sufficiently
to give reliable seed. Most of the seed used in Florida is grown
in Maine. For fall planting, the seed may be taken from the
spring-grown Florida crop. It should be kept over summer
spread out in a dry place, and 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 tubers are large, and are to be planted in three and
one-half foot rows, about twelve bushels per acre will be re-
quired for seeding. Where the seed potatoes are of moderate
size, ten bushels per acre is considered good seeding. When
the seed is to be cut, it is best to have it done a few days before
planting. Mix a little lime through the pile; it has a preserving
effect on the cut surfaces.
The varieties that have given best results in Florida are:
Spaulding's Rose 4, Bliss Triumph, and Irish Cobbler. Spauld-
ing's Rose 4 is the favorite for winter planting. It is a smooth
potato, grows rapidly, matures early and is a good shipper.
Bliss Triumph is equally as satisfactory for fall planting.
An imperfect stand may be due to planting immature or
diseased seed, too deep planting on soils with poor drainage,
too shallow planting where there is insufficient moisture, or
planting on new land that has not been thoroughly prepared.
Where a stand is imperfect it is impossible to get the maximum
yield even though all other conditions may be the best. Un-
favorable conditions must be avoided to make Irish potato
growing profitable in Florida under the expensive cultural
methods usually practiced.
Irish potatoes require frequent cultivation as soon as the
danger from injury by cold is past. If the weather is dry
frequent cultivation is most important to conserve soil moisture.
When the rainfall is plentiful, especially on soils that have a

Florida Agricultural Experiment Station

tendency to become compact, 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 crop
is planted in high ridges a V-shaped cultivator that will stir the
bottom of the furrow and the sides of the banks does the best
work. Where the ridges are not high, an ordinary cultivator
will serve the purpose, and in the event of heavy rains the dirt
may be thrown back to the banks with a plow. Many growers
use the disk cultivator when the crop is young. The inner disks
are set higher than the outer ones, very much as is done for
making the ridges.
For marketing, it is not necessary that the Irish potato
should be thoroughly ripened. When the crop has reached a
marketable size, and the skin slips on pressure of the thumb,
the potatoes are ready to dig; but where 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 set-
backs, it should be ready to dig at from eighty to ninety 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-digger. In small
areas they may be dug more cheaply with hand tools.
The usual shipping season is during April and May, when
there is a good demand for new potatoes in Northern markets.
Florida potatoes reaching distant markets later than this
usually bring a much lower price; hence the advantage of
marketing as early as possible.
The potatoes are graded according to size, either by hand
or machine; machine grading is preferable as the grading is
more uniform. They are then barreled and shipped in car lots
by freight. The cost of shipping by express is prohibitive ex-
cept for the earliest shipments or when exceptionally high
prices prevail.
Seventy-five barrels per acre is a heavy yield. The aver-
age should be about forty barrels per acre.
In all sections of Florida, Irish potatoes can be used in a
rotation of crops. In the largest potato growing sections it is

Bulletin 133, Irish Potatoes

a common practice to plant corn after potatoes. The corn may
be planted close to the potato rows before digging and if dug
with hand tools the digging of the potatoes gives the corn cul-
tivation. When the corn is about mature cowpeas are planted
between the rows giving a third crop off the land. Where cow-
peas 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 lands in a good
physical condition. By such a rotation the land may grow
satisfactory Irish potato crops several years in succession with-
out detriment to the soil. Without a proper rotation of crops
the potato yield will be reduced.
As Irish potatoes grow best in a soil well drained, yet
holding plenty of moisture, irrigation will go a long way to-
ward insuring a profitable yield when the rainfall is only
average or below. When rains are frequent and the soil is
deeply prepared and in a good physical condition, irrigation
may not be necessary on low hammock or flatwoods land. On
high hammock, rolling pinelands, or even in drained-out muck
ponds or lake bottoms, irrigation is usually necessary for good
yields. In unusually dry seasons there is a great possibility of
failure in nearly all Florida soils without some artificial system
to supply water to the crop, as the tubers will stop growing
unless they have sufficient moisture.
In the artesian areas of Florida where the land is level,
surface irrigation from artesian wells can be practiced eco-
nomically. When the water must be pumped into a reservoir
and then piped into the field, the cost is so increased that the
advisability of installing such a system for Irish potato grow-
ing alone is questionable.
Since Irish potatoes give the best yields when planted on
moist lands there is danger of injury by cold to the winter-
planted crop. A frost will not cause serious injury, but when
the temperature ranges between 26 and 32 degrees F., the crop
is usually injured. Some of the injury may be prevented and
perhaps overcome by adopting the proper cultural methods.
Lands that have a heavy crop of vegetation should be
plowed deeply as early as October so that all vegetable matter

Florida Agricultural Experiment Station

will decay and become thoroughly incorporated with the soil
before planting.
Thoro soil preparation before planting is also a good
frost preventive because the crop will not necessarily have to
be cultivated for some time after the seed is planted. On
fields where part of the crop has been cultivated there is
usually a marked difference in the cold injury, therefore give
as little cultivation as possible until after the danger from
freezing is past. Avoid cultivation if weather reports indicate
a freezing temperature during the following forty-eight hours.
Injury from cold may also be prevented by filling the fur-
rows with water or by permitting overhead irrigation water to
flow during a freezing period. Small plants may be protected
by covering 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
immediately 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 below the frozen part. When the crop has been seri-
ously injured, every effort should be made to induce quick
growth. If the soil is dry it is advisable to irrigate. Cultiva-
tion, too, will stimulate growth and is beneficial. Applications
of fertilizer at this stage, however, are of little benefit. If
the injury is following by drying winds and poor conditions
for growth, the crop very likely will be cut short.
LATE BLIGHT.-Late blight is caused by a fungus, Phytophthora in-
festans, which attacks both the tops (stems and leaves) of the plant, and
the 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 dis-
ease. In a few days the whole field looks as if the plants have 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, changing 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 and the tubers decay
Methods of Control.-1. If possible, secure seed from a reliable grower
who can guarantee the seed to be free from disease.

Bulletin 133, Irish Potatoes

2. In selecting the seed for planting, discard all potatoes showing
signs of decay.
3. The disease can be kept in check by spraying the plants thoroughly
with bordeaux mixture 5-5-50. Spraying should begin when the plants
are four to six inches high and be repeated every second week until about
10 days before digging the tubers.
EARLY BLIGHT.-This disease caused by a fungus known as alternaria
solani may be mistaken for late blight, for at a distance the two appear
similar, and frequently they are found associated upon the same plant or
even upon the same leaf.
The disease appears only on the tops; the tubers are not attacked.
The diseased areas are small and almost circular in outline, though fre-
quently the spots run together, in which case the circular outline may
almost disappear. The diseased areas often show concentric rings, a pecu-
liarity 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 to the
crop in Florida.
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 main stem be the
point first attacked, the whole plant droops. Following this wilted condi-
tion the plant soon dries up and loses its foliage.
The disease is caused by bacteria which live in the inner tissues of the
plant. If the stem of a diseased plant be cut through, a dark layer of
tissue just underneath the bark can be seen.
The germs make their way downward through 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 diseased spots. This substance contains
almost pure cultures of the bacterium causing the disease.
The disease is spread largely by grasshoppers, leafhoppers and suck-
ing insects, which carry the disease to healthy plants.
Methods of Control.-1. Infected seed should not be planted.
2. Rotation of crops should be practiced, avoiding crops subject to
the disease.
3. The wilted plants should be taken out and destroyed.
4. Destruction of insects, especially aphis.
The disease seems more prevalent on rolling dry lands, so that by
keeping the soil moist by irrigation 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 alkaline soil
but does not thrive in an acid one, consequently an application of lime, or
wood ashes, making the soil neutral or alkaline, favors the development of
this disease. Fresh stable manure applied just before planting, frequently
causes scabby potatoes.
Treatment of Seed.-
Formaldehyde ...--............ 1 pint or Corrosive sublimate...........1 ounce
Water ..............-------.................30 gallons Water ....................................------------8 gallons
Soak the seed for two hours in Soak the seed for one and a half
this solution, hours.

University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs