Florida Cooperative Extension Service / Institute of Food and Agricultural Sciences / University of Florida / John T. Woeste, Dean
POTATO PRODUCTION GUIDE
Florida potato production includes both winter
and spring seasons. Total planted acreage in the
state usually averages close to 30,000.
The bulk of the winter crop is sold for table stock,
with a few sold to the potato chip industry. The
red-skinned cultivars are the dominant types grown
in south Florida for the winter season, but white-
skinned cultivars are also becoming more impor-
tant for both the fresh and chip market.
Spring potatoes are grown in all areas of the state,
ranging from Ft. Myers to Pensacola in west Flor-
ida. The Hastings area, which includes areas in
Flagler, Putnam and St. Johns Counties, is the
major spring production area. Both white- and red-
skinned cultivars are grown for the spring crops,
with the white-skinned types being pre-dominant.
The bulk of the spring crop is sold for chips, with a
few being sold for table stock.
Good-quality seed potatoes are necessary to insure
success in the production of this crop in Florida.
Growers should always use certified seed. In addi-
tion, care should be taken to protect seed stock from
cold injury, overheating, etc., during the period
between arrival on the farm and planting. Seed pie-
ces should be placed in a dry area with sufficient
Seed Piece Treatments
Dormancy. Chemical treatment for breaking the
"rest period" of the potato tuber is recommended
only for the winter crops in south Florida. Gibberel-
lic acid (GA) is used to break dormancy in those
cases where need has been established.
Commercial formulations of GA are available.
Freshly cut seed-pieces are sprayed with or dipped
in a 1 ppm solution (Red LaSoda and other red cul-
tivars may need to be treated with 2 ppm of GA). GA
may be combined with treatment for scab and seed
Decay Control. Care should be taken to remove
any decayed seed potatoes from the lots before cut-
ting seed pieces. Decay organisms can be spread to
clean seed pieces by knives coming in contact with
rotting tubers. Cutting knives and machines should
be cleaned regularly with a 100-150 ppm free-
chlorine solution for control of soft rot and other
Spacing and Seeding
North and central South
Distance between rows 36"'to 42" 36" to 42"
Distance between plants 8" to 12" 6",to 9"
Planting depth 3" to 4" 3";to 4"
Seed-piece size 11/2 to 2 oz 114 to 11/2 oz
Seed required/acre 14-2400 Ib 14-2000 Ib
W. M. Stall, Extension Vegetable Specialist
Mark Sherman, Postharvest Extension Vegetable Specialist
Potato seed-piece fungicide treatments are often
helpful in obtaining better stands and yields. Pro-
tection from invasion of soil-borne organisms may
result in a reduction of seed-piece decay after plant-
ing. Seed treatment is not, however, a cure for lack
of sanitation, poor seed handling and for poor seed
environments either before or after planting.
Area/Dates Days to harvest
South Florida September to December 85-110
Everglades: Sept. 15-Oct. 5 and
Jan. 10-Feb. 15
Southwest: Oct. 10-Oct. 31
Dade County: Nov. 15-Jan. 1
Central Florida December to February 85-110
North Florida January to February 85-110
Hastings: Dec. 20-Feb. 15
Potato cultivars differ in skin color, time of
maturity, yield, appearance and marketing qualities
as well as in disease resistance. A cultivar that may
be excellent when grown in north Florida may not
do well in south Florida and vice versa. Before plant-
ing an unknown cultivar, check with your local
Extension Agent and consult the updated recom-
mended variety listing for Florida from your local
The following are cultivars that have demon-
strated excellent results in at least one area in Flor-
ida and are recommended for production:
Sebago: Standard white cultivar. Excellent for
chips. Smooth, good shape. Some disease resist-
ance to brown rot.
Atlantic: White tubers are excellent for chips. Tub-
ers smooth, block-round in shape. Susceptible to
brown rot but resistant to corky ringspot.
LaChipper: Medium-maturing Irish Cobbler type,
white skin with very white flesh. Good chipper.
Superior: A white cultivar resistant to corky ring-
spot disease. Should only be planted late in season
since it recovers poorly from adverse weather.
Hudson: A white cultivar adapted to marl soils.
Oblong tubers, white skin and shallow eyes. Res-
istant to corky ringspot.
Pungo: Round, white cultivar, recommended only
where corky ringspot virus is present in the soil.
This variety is highly susceptible to bacterial
Chieftan: Dark red, slightly russeted skin. Smooth,
uniform shape with shallow eyes. Good yields.
Red LaSoda: A dark red-skinned cultivar, with
attractive, fairly smooth, white flesh. A good
yielding, medium early variety of high quality.
Standard red cultivar in northeast Florida. Sus-
ceptible to brown rot and corky ringspot.
LaRouge: Medium to late-maturing. Smooth attrac-
tive red skin, white to cream-colored flesh. Ear-
lier than LaSoda. Standard cultivar in Dade
Other Cultivars: Norchip, Kennebec, Centennial,
Potatos are grown in a wide range of soil types in
Florida. Grower fertilizer programs should be based
on soil type, soil pH, cultivar and irrigation use,
along with the cropping history and soil test analysis
of the fields to be used.
Soil pH. Potatoes grow over a wide pH range (5.0
to 7.8). Low and high soil pH reduce phosphorus
availability along with minor element availability.
In mineral and organic soils where scab-resistant
varieties are grown, a pH of 6.0 to 6.5 is optimum.
Where scab is a problem and scab-susceptible cul-
tivars are grown, the pH should be maintained
between 5.0 to 5.2 or above 7.2. Nutrient levels then
should be adjusted for availability.
Micronutrients. A general guide for adequate
micronutrients in mineral soils is the addition of 5 lb
of manganese (Mn), 3 lb of copper (Cu), 3 lb Zinc
(Zn), 4 lb iron (Fe) and 1.5 lb of boron (B) per acre.
These micronutrients can be obtained from mix-
tures of oxides, sulfates and chelates. Higher rates
are necessary to overcome the tendency of micro-
nutrients to be tied up by the organic matter in soils
and by the high pH of marl soils.
On new organic soils, a broadcast application of 12
lb of Cu, 8 lb of Mn and 1 lb of B per acre is recom-
mended before any crop is planted. Where Mn levels
are low, dolomitic limestone can be used or magne-
sium sulfate (MgSO4) can be added to the fertilizer
Primary nutrients. The common forms of nitro-
gen fertilizer are nitrate, ammonium and urea.
Potato plants can utilize either the nitrate or ammo-
nium form in the soil. Where leafroll has been
observed, the fertilizer's total nitrate/nitrogen pro-
portion of the total nitrogen should be increased to
35 percent or greater. Peat or muck soils require
little or no supplemental nitrogen due to the high
levels of nitrate/nitrogen normally found in these
soils. Excess nitrogen levels can decrease tuber
quality, yield, and grade.
Phosphorous fertilizer is needed in all Florida
soils to produce a good crop of potatoes. Soil analysis
can generally be used to identify residual phospho-
rus from previous crops. It should be noted, how-
of vascular discoloration from vine killing:
1. During hot weather, use chemical vine killers
only when soil moisture is adequate.
2. When unable to control soil moisture during
hot weather, use lower rates of the material or
use a chemical known to kill the vines slowly.
3. Mow the tops before applying the vine killer.
Harvesting. Most Florida potatoes are mechani-
cally harvested directly into bulk trucks or trailers
that transport the tubers to packinghouses. Growers
may lose 20 percent of their potential income through
potato injury at harvest. Losses can be minimized by
management attention to the following points:
1. All equipment should be available and opera-
tional to avoid delays in harvesting.
2. Precautions should be taken before harvest to
anticipate and minimize problems caused by
clods, weeds and vines.
3. Apron pitch (length of each individual link
from hinge point to hinge point) should be as
wide as possible, consistent with the size and
shape of the potatoes being harvested. Tubers
of round cultivars are more adaptable to wide-
pitch aprons than tubers of long cultivars.
4. Only an alert, capable person should operate
the harvester. The crew should be trained to
work as a team, with each person assigned
clearly defined responsibilities.
5. The harvester/operator needs to insure: (a)
that the blade of the harvester is set deep
enough to prevent cutting of the tubers but not
so deep to create a soil overload for the apron
capacity; and (b) that forward travel and apron
speeds are consistent with good soil and tuber
separation without using severe, tuber-damag-
6. Drops should be kept to six inches or less if
possible. Padding should be used wherever
potato bruising might occur. Rubber-covered
apron links are advisable. Padding should be
placed in areas of bulk trucks where loading
begins. Operators should build the load to full
height in the padded areas first, then continue
loading on previously built mounds to reduce
Bruise detection. Different methods are used to
detect blackspot and shatter, the two major types of
potato bruises. A proper check for total bruise
damage must include both blackspot and shatter
Blackspot appears as relatively uniform, dis-
colored areas beneath the skin. A blackspot bruise
generally does not penetrate deeper than one-quarter
inch and usually does not rupture the skin. Bruised
potato tissue begins to discolor six to twelve hours
after the injury occurs and may require 24 hours to
develop fully. Blackspot bruises are detected by
peeling tubers after allowing 24 hours for dis-
coloration to develop.
Shatter bruises appear as cracks or fissures with
the flesh discoloring at the edges. Unlike blackspot,
shatter bruises usually break the skin and may
penetrate deeply into the tuber. Shatter bruises and
other defects that break the tuber skin can easily be
detected within a few minutes with a catechol chem-
ical treatment applied to the outer surface of the
potato. The short delay for results makes the cate-
chol method ideal for helping harvester operators
check harvester performance and make necessary
adjustments to minimize tuber injury. It is also use-
ful for isolating equipment or handling steps caus-
ing damage during packing operations.
Packing. Generally, potatoes are unloaded from
bulk trucks into water flumes for conveyance to the
packing lines. Where ample water is available,
fluming has the handling advantages of cushioning
potatoes as they are unloaded and removing loose
dirt. Care should be taken to insure that the potatoes
drop directly into water as they are unloaded and
not off the metal, wood, or concrete sides of the
From the flume, potatoes are elevated to the
grading lines. Graders should be stationed at this
elevator to remove badly decayed or injured tubers
and other foreign objects. To do a good job of
grading, it is essential that graders are provided
with adequate lighting.
From this elevator, potatoes generally pass
through a washer to remove any remaining soil.
Addition of chlorine to the wash water at 100-150
ppm free chlorine may help in preventing the
spread of decay-causing organisms. If the water is
recycled or reused, chlorine should be added to
prevent the buildup of disease-causing organisms
and inoculation of healthy tubers. For more in-
formation on chlorination, see Vegetable Crops Fact
Sheet, VC-1, "Water Chlorination for Vegetable
After washing, potatoes pass over a sizer to
remove undersized tubers. Following this step,
potatoes usually pass over sponge-rubber drying
rolls to remove some of the water. Further drying
may be required to minimize decay problems. At
high temperatures, a thin film of water on tubers
can rapidly lead to anaerobic internal conditions,
making them especially susceptible to soft rot bac-
teria. However, if supplemental heating is used for
drying, it should be one of the last steps just prior to
packaging, whenever possible. This practice mini-
mizes energy consumption because all culls have
and, if necessary, treated with fumigants or systemic
insecticides. The history of insect migrations and
life cycles also will aid in control decisions.
For specific information on insect control, consult
your County Extension Agent and/or Circular 193;
"Insect Control Guide."
Diseases. Pathogenic diseases are encountered by
potato growers each year. These diseases are caused
by bacteria, fungi, virii and mycoplasms.
Prevention and control of the many diseases
affecting potatoes vary widely depending on the
specific disease. There are, however, some practices
that apply to all diseases, including (1) use of
properly handled certified seed; (2) following a
regular sanitation program; (3) use of fungicides at
the proper rates and with the proper timing; and (4)
use of correct cultural practices to reduce the envir-
onment for disease buildup and spread.
Diseases caused by bacteria, such as bacterial soft
rot, black leg, brown rot (southern bacterial wilt),
ring rot and common scab are prime examples of
control by cultural techniques. These diseases must
be controlled by certified seed, sanitation, resistant
varieties, and soil pH (in the case of scab).
Diseases caused by fungi include Fusarium and
Verticillium wilt, early blight, late blight, sclerotinia
(white mold), rhizoctonia and silver scurf. The
controls for these diseases are varied and include the
use of specific fungicides.
Virus diseases usually are not a serious problem
in Florida, providing certified seed is used. An
exception is corky ringspot in the Hastings area.
A few disorders of potatoes are non-pathogenic or
are physiological in nature. A few of these disorders
which are found in Florida are: hollowheart, knobbi-
ness or "second growth," greening, internal black
spot and air pollution damage. Many times, these
disorders can be confused with symptoms from
pathogenic diseases. Correct disease identification
must be made before control measures are attempt-
Weeds. An effective weed control program takes
into account the primary weed species in the area,
cultivation and available herbicides. Weed problems
can be specific for different fields and production
areas. Weed control practices and herbicides should
be selected for control of the primary weeds present.
Perennial grasses, including nutsedges, Bermuda
grass, Johnson grass and quackgrass, many times
are the most difficult to control. A combination of
cultural practices and specific selected herbicides is
needed for control. These grasses, which cause yield
reductions and decrease harvest efficiency, can also
reduce tuber yield by rhizome penetration of the
Early cultivation, or preplant/preemergence
herbicides coupled with a later cultivation or post-
emergence treatment, usually will provide adequate
early season control of broad-leaf weeds and annual
grasses. Varieties that form dense canopies with
their foliage also aid in effective weed control.
Harvesting and Handling
Potato harvesting is a highly mechanized operation
in Florida. Mishandling during harvesting has a
highly detrimental effect on the quality of potatoes
delivered to processors or to the fresh market.
Attention to the details described below will help
growers, packers and shippers preserve the high
quality necessary to maintain a competitive position
in today's marketplace.
Vine Killing. Harvesting is easier when the
potato vines are dead. With modern, high-yielding
production techniques, green vines are maintained
later in the growing season and it has become
necessary to kill the vines in preparation for harvest.
Vine killing has two major advantages from the
quality standpoint: (1) it reduces bruising, and (2) it
encourages better "skin set." Less bruising is the
result of easier separation of vines and tubers.
During tuber growth and development, the skin
(periderm) is constantly being sloughed off. Timely
killing of potato vines effectively stops tuber growth
and allows the periderm to thicken and toughen.
This "skin setting" results in a more attractive
potato that has better resistance to postharvest
water loss and decay than tubers harvested from
Vine killing usually should start two to three
weeks before harvest, depending on the cultivar,
growing conditions, and time of year. Three general
methods are used for vine killing: (1) mechanical, (2)
chemical, and (3) combinations of the two. Mowing
and pulling are possible mechanical methods.
Machines should be adjusted to avoid disturbing the
soil, to prevent tuber exposure to sunlight, frost, or
mechanical damage. Several herbicides are labeled
for vine killing (consult your County Agent for
current recommendations). Vine killing is costly
and difficult to accomplish; therefore, it should be a
well-planned and carefully executed operation.
Vine killing can sometimes adversely affect tuber
internal quality. This problem appears as a dis-
coloration in the vascular ring, usually confined to
the stem end. Occasionally, vascular discoloration
may be severe enough to reduce tuber grade. The
occurrence of vascular discoloration is usually asso-
ciated with rapid vine killing. Adoption of one of the
following practices will help minimize the possibility
ever, that phophorus is much less available at low
and alkaline pH levels, and that applications should
be adjusted accordingly. Phosphorus is needed pri-
marily in the early stages of growth and should be
applied at planting. Supplemental applications of
fertilizer need not contain phosphorus.
Potassium is usually supplied as potassium sul-
fate, potassium chloride or potassium nitrate. Pot-
assium chloride (muriate form) can contribute to a
greater salinity problem in many soils and some
evidence supports the theory that it may contribute
to lower specific gravity and washed-out skin color
in some cultivars.
Timing and placement. Fertilizer applications
may be made before planting, during the planting
operations, after planting, or in combination as split
In areas where a history of salt injury has been
noted, half the fertilizer should be applied broadcast
before planting with the remainder applied as
banded sidedress applications.
In the Hastings area, the recommended initial
application is 150-200-150 of N-P2Os-K20 at plant-
ing with a sidedress of 50-0-50 made before lay-by.
The application rates of phosphorus and potassium
should be adjusted by soil test.
The primary economic pests of potatoes in Florida
include nematodes, weeds, insects and disease-
causing pathogens. Non-biological factors such as
air pollutants can also cause stand and/or yield
The control of pests in Florida integrates the use
of cultural, biological, mechanical and chemical
means. Specific information and pesticide recom-
mendations for the control of pests on potatoes
change frequently. Updated information can be
obtained through your County Extension Agent and
through several extension publications which are
Nematodes. Potatoes are susceptible to nematode
injury. Some nematodes, such as the root knot nema-
tode, can reduce plant growth by attacking the
roots, or can attack the tuber, causing superficial
The stubby root nematode attacks the roots and
causes reduced yields. Nematodes can also increase
the severity of some diseases such as Verticillium
Planting in infested fields should be avoided
whenever possible. Crop rotation and flooding are
possible means of helping to control nematodes. If
infested soil must be used, nematicides should be
applied. Specific recommendations can be found in
Bulletin 707, "Nematode Control Guide," or can be
obtained from your local County Agent.
Insects. Insect control is an important considera-
tion in potato management. Specific insect problems
in Florida vary with the production area. However,
there are several insect pests that can cause varying
amounts of damage in most production areas. Aphids
are an example. In addition to direct damage by
feeding, the spread of potato virus diseases by
aphids can be a serious problem.
The cutworm, tuberworm and wireworm, along
with the larvae of the cucumber beetle, can cause
damage to potato tubers and cause loss of grade
Many times, Lepidopterous larvae, such as the
armyworms (southern beet and fall), along with
loopers and the cutworm, can build up and cause
severe problems. Stinkbugs, fleebeetles, leafhoppers,
grasshoppers and the Colorado potato beetle are
other insects that can cause extreme damage to
Economic control of most of these insect pests is
accomplished primarily with insecticides. Appli-
cations can be timed for most of these pests by
periodic scouting of fields and application of in-
secticides when specific thresholds have been reach-
ed. Wireworm levels can be sampled before planting
Total' Supplemental applications
Soil Actual Ib/acre Actual Ib/acre No. of
each application appli-
N-P2Os-K,O N-P2Os-K20 cations
Mineral2 175-200-200 50-0-50 1 to 2
Mineral2 120-160-160 50-0-50 0 to 1
Muck and peat 0-160-240 -
Marl 80-160-160 30-0-30 0 to 2
'Total N-P20,-K,O needed to produce crop. If supplemental applications are to be made, reduce initial N and K,O applications
2AII acid mineral soils. Excludes alkaline soil.
been removed and tubers have had time to air dry.
A good grading crew is essential to making a
quality pack. Packinghouse managers need to insure
that: (1) there are enough trained graders to perform
the job; (2) potatoes move past graders within a
comfortable reaching distance; and (3) lighting is
adequate. A reverse-roll grading table insures that
graders have an opportunity to view all tuber
Tubers are usually separated further according to
size. With the increased demand for uniform-count
packs of potatoes for the food service industry,
automatic weight sizing can be advantageous.
Grades. Grade standards describe the quality
requirements for each grade of a commodity, giving
the industry a common language for buying and
selling. United States standards for potatoes specify
four grades: U.S. Extra No. 1, U.S. No. 1, U.S.
Commercial, and U.S. No. 2. Size is often specified
in connection with the grade. A copy of the U.S.
grades can be obtained through your local County
Containers. Potatoes for processing are generally
shipped in bulk. Fresh market potatoes are packaged
in a wide variety of containers. Five- and ten-lb
consumer packages are usually placed in a master
bag or carton holding 50 lb. Bulk containers are
available for moving consumer packages to large
retail stores. Potatoes are often moved to repackers
in bulk, or jumble-packed in 50-lb bags or cartons.
As part of a national movement to standardize
shipping containers, shippers are urged to use a
container with one of the following outside length
and width dimensions: 23.6" x 15.7", 19.7" x 15.7",
19.7" x 11.8", or 15.7" x 11.8". Adoption of one of
these standards containers will facilitate palletized
handling throughout the food distribution system.
The 19.7" x 11.8" container was successfully used in
Florida as a master container for ten 5-lb consumer
packages and 50-lb jumble-packed packages.
Labeling. The inadequate product identification
information currently found on shipping containers
causes many problems in the food distribution
system. It is recommended that 65 percent of the
surface of at least two sides, preferably four sides, of
all shipping containers be used for product identi-
fication information (commodity, size or count, culti-
var, weight and grade). The remaining 35 percent
should be used for brand name, shipper and address.
For the 19.7" x 11.8" container described above, it is
suggested that the minimum height of lettering for
size/count, cultivar, and commodity be one inch; for
origin, weight, and grade, a minimum letter size of
one-half inch is suggested.
Shipping and storage conditions. Generally,
Florida potatoes are not stored, or are stored for only
a short period. To prevent reduced sugar accumula-
tion, potatoes destined for processing into chips or
french fries should not be exposed to low tempera-
tures. Storage and transit temperatures should be
maintained between 60-65 F for processing pota-
toes. For fresh market, 50' F is suggested for
storage and transit. Lower temperatures are possible
for fresh market potatoes, but they are unnecessary
for decay control and they increase tuber suscepti-
bility to blackspot bruises as well as increasing
energy requirements. Relative humidity should be
maintained between 90-95' for both fresh market
and processing potatoes.
This publication was promulgated at a cost of $837.95, or 31 cents per copy, to extend current production
information to commercial potato producers. 2-2.65M-83
COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, INSTITUTE OF FOOD AND AGRICULTURAL
SCIENCES, K. R. Tefertlller, director, in cooperation with the United States Department of Agriculture, publishes this Infor-
mation to further the purpose of the May 8 and June 30, 1914 Acts of Congress; and is authorized to provide research, educa- I
tional Information and other services only to individuals and institutions that function without regard to race, color, sex or
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residents from County Extension Offices. Information on bulk rates or copies for out-of-state purchasers is available from
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publication, editors should contact this address to determine availability.