Peppers

Taxonomists have only recently begun to agree
regarding classification of the domesticated species of Capsicum.
Although five species are described, only two, C. annuum and C.
frutescens
have any significance commercially in the U.S.A. Early species
separation on the basis of fruit shape, color and position are of little
taxonomic value. Flower and seed color, shape of the calyx, the number of
flowers per node and their orientation, are the primary separating
characteristics.

C.
annuum
is the most important domesticated species in the U.S.A. and is
the species to which all bell peppers, and all the peppers listed below belong
(unless specified otherwise.) The only C. frutescens pepper of any
significance is Tabasco. The Tabasco pepper is difficult to cross with C.
annuum
types. Hot peppers may belong to any of above species and others.
The C. chinense varieties Habanero and Scotch Bonnet are considered the
hottest.

The
interest in peppers extends to their nutritive and medicinal value in that
peppers are a recognized source of Vitamins C and E and are high in
antioxidants. These compounds are associated with prevention of cardiovascular
disorders, cancers, and cataracts.

Peppers
are a warm-season crop and need a long season for maximum production.
Temperature has a large effect on the rate of plant and fruit growth and the
development and quality of the red or yellow pigments. Ideal temperature for
red pigment development is between 65°F and 75°F. Above this range the red
color becomes yellowish, and below it color development slows dramatically and
stops completely below 55°F.

Many
excellent pepper varieties are available. Test several and select the ones that
do well under your production system, and meets your market needs.

In
cooler areas, pepper growers may improve their chances for successful pepper
production by using raised beds ( to improve drainage), by using plastic
mulches (to warm the soil and control weeds), and drip irrigation (to promote
uniform moisture and fertilizer delivery), and by staking plants (to reduce
plant breakage and disease – improves air movement). These practices are
especially important when the goal is to produce colored peppers (red, yellow,
orange etc.) which have greater quality requirements and higher values, and
take longer to mature.

ETHEPHON
FOR COLORED PEPPERS

When
colored peppers are desired, a foliar spray of ethephon (Ethrel) may be used to
promote early, uniform ripening and coloring, or to ripen the partially ripe
fruit remaining at the end of the harvest season. The effectiveness of Ethephon
is highly dependent on ambient temperature. Check the Ethephon label for
complete instructions and regulations.

Plant
size and the cover provided the fruit is important in reducing risk from
sunburn. This risk may also be reduced by selecting plant population density
and row spacings that allow for good fruit cover.

SOIL

Peppers
grow best on well-drained, moderately fertile soils. Use a soil test to
determine fertilizer and liming requirements. Peppers grow best at soil pH
between 6.0 and 7.0. Adjust soil pH to near neutral (7.0) for maximum yields.

To reduce
risk from Verticillium wilt and other diseases avoid using fields in
your rotation plans in which eggplant, tomato, pepper, potato, strawberry or
cranberries have been planted.

SEED AND SEED TREATMENT

Pepper
seed numbers approximately 72,000 per pound. Bell peppers are not normally
direct seeded and this practice is not recommended for cooler areas. Use high
quality, fungicide treated seed in the production of transplants. Some seed
companies now offer “vigorized’ or "conditioned” seed which has
better germination under cool soil conditions. Peppers are sensitive to
damping-off.

In
direct-seeded plantings a pop-up fertilizer solution may be helpful. Spray
directly on the seed a solution of 2-6-0 at 1 pint per 100 lineal feet of row
(use ½ this rate on sandy soils). A 2-6-0 solution is equivalent to 1 part of
10-34-0 liquid fertilizer diluted with 4 parts of water.

TEMPERATURE REQUIREMENTS

Pepper
is a warm-temperature vegetable and requires a long growing season. Transplants
which are grown should be kept close to the following temperatures: Days:
65°F-85°F. Nights: 60°F-65°F. Temperatures above 95°F may result in flower bud
drop. Highest yields are obtained when soil temperatures remain in the
70°F-75°F range. Soil temperatures below 68°F may result in substantial yield
reductions.

The
use of clear plastic mulch applied over herbicide treated soil, or black
plastic mulch, or the new IRT (wavelength-selective) mulch is strongly
recommended.

Many
pepper varieties are grown in greenhouses, however few are reported to tolerate
cool temperatures that sometimes occur in off-season greenhouse production.

TRANSPLANT PRODUCTION AND TRANSPLANTING

It
takes between 3 and 4 ounces of seed to produce enough plants for an acre.
Seeds should be planted in a heated greenhouse 6 to 8 weeks before the field
transplanting date. When growing transplants in unheated greenhouses, cold
frames or field transplant beds, 8 to 14 weeks may be necessary. Seedlings are
transplanted to other flats when the first true leaves are l.5 inches long and
spaced 2 to 2.5 inches apart in the greenhouse or plant bed. At all times
handle pepper seedlings with care because they are easily broken or damaged.
Harden transplants for about a week before transplanting to the field by reducing
moisture and maintaining a temperature of 55°F to 65°F. This will give
resistance to wilting and sunscald.

Transplant
spacing and exposure to light and temperature have a major effect on transplant
vegetative growth and quality. Avoid crowding, provide adequate light, and use
minimal night temperatures to reduce risk of spindly growth.

Apply
a starter fertilizer solution to the transplants when transplanting to the
field. Select starter fertilizers that have the highest level of phosphorus
available, such as 10-52-17, 11-48-0,11-55-0 dry fertilizers or 10-34-0 liquid
fertilizer. Make up a stock solution of 3 lbs of the dry, such as 10-52-17, or
2 pints of liquid 10-34-0 per 50 gallons of water. Use ½ pint of this stock
solution per plant, applying the solution directly to the plant roots when
setting in the field. You will need about 13 fifty-gallon batches to transplant
an acre.

Depth
of transplanting has normally been to the top of the roots or root ball.
Research from Florida with the variety Jupiter suggests that pepper transplants
may benefit from being set deeper, up to the first true leaf. Thirty days after
transplanting, plants planted to the first true leaf had more leaves, greater
plant dry weight, more blooms and less lodging than transplants planted to the
cotyledons or to the top of the root ball. Other data from Pennsylvania suggest
caution however. Soil temperature and moisture would be important
considerations.

Greenhouse
peppers for harvest of red fruit is approximately 5 months later.

SPACING

Space
rows, or pairs of rows about 18-36 inches apart. Plants should be 12-l8 inches
apart in the row and between pairs of rows, depending on method of
transplanting and transplanter capability. These spacings represent a plant
population of from 10,000 to 29,000 per acre

Where
sunscald may be a problem, the risk of sunscald can be reduced by using paired
rows and closer spacings between rows and plants.

Leave
roadways across the field at about 150 foot intervals to facilitate carrying
pails of peppers to collection locations if a harvester aid and bulk loading is
not used.

When
using plastic mulch, plant 2 rows of peppers per mulch strip, using 36
inch-wide plastic. Space plastic strips 5-6 feet apart. Use drip irrigation
tubing under the plastic mulch between the two pepper rows, with drip emitters
at 9-inch spacing down the row.

In
greenhouse production, allow 3.0 to 3.5 square feet/plant. Plants are pruned to
a 2-stem training system. After 10-12 leaves have developed, the plant forks,
and a flower develops at the fork. Two or three branches are produced, of which
the two strongest are chosen for further production. These must be supported by
a string or post, and all subsequent branches removed after the 2nd leaf.
Restrict fruit set on the two stems until at least 3 or 4 leaf axils have
formed or stem growth and subsequent fruit set will be greatly reduced.

FERTILIZER

A soil
test is the most accurate guide to fertilizer requirements. The following
recommendations are general guidelines for loamy soils or when organic matter
exceeds 2.5 %:

Nitrogen:
100-150 lb N/acre. The use of ammonium N sources may aggravate blossom-end rot
by interfering with calcium uptake.

Sidedress
with 35-50 lb N/acre after the first flowers are set. Where mulching and
trickle irrigation are practiced, additional nitrogen can be fed through the
trickle irrigation system at l5 lb/acre when the first fruit begins to set and
an additional l5 lb/acre four weeks after. To prevent clogging or plugging from
occurring, use soluble forms of N (urea or ammonium nitrate) and chlorinate the
system once a month with a l0 to 50 ppm chlorine solution. Chlorinate more
frequently if the flow rate decreases.

Phosphate:
100-150 (P2O5) lb/acre

Potash:
100-200 (K2O) lb/acre depending on soil test. When K is adequate, excess K has
been reported (Florida ‘94) to reduce wall thickness without increasing yield.

Sulfur:
30-35 (S) lb/acre

pH:
Add lime if below 6.0

GROUND MULCHES AND ROW COVERS

The
use of clear plastic mulch applied over herbicide-treated soil, or black
plastic ground mulch, is recommended. The use of ground mulch increases soil
temperature, conserves soil moisture, and controls weeds, increasing yields and
is strongly recommended. For black plastic mulch to increase soil temperature,
it is critical that the soil surface be smooth and that the plastic be in close
contact with the soil. This can only be achieved by laying the plastic with a
machine designed and properly adjusted for this task. Clear plastic mulch is
superior for heat transfer but does not control weeds without herbicide
application.

A new
generation of plastic mulch films allows for good weed control together with
soil warming that is intermediate between black plastic and clear film. These
films are called IRT (infrared-transmitting) or wavelength-selective films.
They are more expensive than black or clear films, but may be cost-effective
where soil warming is important. (See also section on spacing).

Plastic,
spunbonded, and non-woven materials have been developed as crop covers for use
as windbreaks, for frost protection, and to enhance yield and earliness. They
complement the use of plastic mulch and drip irrigation in many crops.

Non-woven
or spunbonded polyester and perforated polyethylene row covers may be used for
4 to 6 weeks immediately after transplanting depending on temperature. Research
in Illinois with the varieties “Lady Bell” and “Bell Boy”,
over a three-year period, indicates that covers should be removed after 650-675
heat units (using a base temperature of 50°F) have been accumulated. Heat units
should be based on temperatures recorded outside the covers but nearby and
calculated as: the sum of ((daily high+daily low)/2)-50°F, with negative values
counted as zero.

Row
covers increase heat unit accumulation by 2 to 3 times over ambient. Two to
four degrees of frost protection may also be obtained at night. Soil
temperatures and root growth are also increased under row covers as are early
yields, and in some cases total yields. Research from Connecticut indicates
that the use of row cover and plastic mulch is particularly cost effective when
growing red, yellow or orange bell peppers for the fresh market.

GIBBERELLIC ACID

Gibberellic acid (GA) is labeled for promotion of pepper plant growth in all
states but California. The label calls for application of 1 or 2 sprays of 1-3
gal/acre in 25-50 gal/acre at 2-week intervals. Sprays should begin about 2
weeks after transplanting. This technique is recommended for areas with short
growing seasons or when low temperatures slow plant growth.

GA is
also labeled for increased fruit set and fruit growth. Apply 1 or two sprays of
1-3 gal/acre in 25-50 gal/acre at weekly intervals during flowering. The high
rate is recommended for areas or varieties with pollination or fruit set
problems. To promote fruit size, apply GA at the beginning of the harvest
period, with the 3-g rate recommended for heavy crop loads.

Caution: For trial
only. Efficacy of GA on pepper has not been confirmed.

IRRIGATION

Water
stress, as exemplified by extremes of drying and wetting, increases incidence
of blossom-end rot. Also avoid over-irrigation after fruit ripens to reduce
risk of fruit decay. Excess moisture on the foliage and fruit may aggravate
this. Morning sprinkler irrigations are helpful in allowing time for foliage to
dry before nightfall.  

Research
has shown that the use of drip irrigation under black plastic mulch is superior
to sprinkler irrigation with black plastic mulch. Yields usually increase
dramatically.

HARVESTING, HANDLING, AND STORAGE

Yields
of 15 to 25 tons/acre of bell peppers may be obtained for processing. Fresh
market yields may range from 500 to 1000 28-lb cartons/acre. When using
appropriate plasticulture techniques, yields of 1428 28-lb cartons/acre have
been reported. Pimiento and dried chili pepper yields range from 2 to 3
tons/acre. Pepper yields are greatly influenced by the number of harvests and
season. As peppers mature their wall thickens. Pick peppers when fruit is firm
and well colored.

Bell
peppers are generally hand harvested as green mature fruit. For fresh market,
or when fruit is to be stored, peppers should be cut cleanly from the plant
using a hand clipper or sharp knife, leaving about a 1-inch section of the
pedicel (stem) attached to the fruit. A clean cut is important as such cut
surfaces heal more quickly. This reduces incidence of decay in storage and
during transport to market. Care should also be exercised to be sure stems do
not cause puncture wounds in harvested fruit.

Maturity
is determined when fruit is smooth and firm to the touch (a function of wall
thickness). Bell peppers for fresh market must also be 3 inches in diameter and
not less than 3.5 inches long to qualify as USDA Fancy. They can also be
harvested red, which are considerably sweeter and more flavorful. Mature
yellow, orange and purple bell peppers, together with red bell peppers
represent a generally higher value product in fresh market channels.

Pixall
(100 Bean St., Clear Lake, WI 54005) manufactures a mechanical harvester
suitable for chile, cherry, and jalapeño peppers. Pixall also makes harvesters
for beans, corn, peas, and spinach. Pik Rite (101 Fairfield Rd., Lewisburg, PA
17837) offers a mechanical harvester for bell, cherry, chili, and banana
peppers. Pik Rite also manufactures harvesters for tomatoes and cucumbers.

Cherry
peppers are machine-harvested most successfully. Cherry types are harvested as
both green and red fruits, and the banana types are generally harvested as
yellow mature peppers. Jalapeño and some cherry peppers have been machine
harvested successfully in Michigan and California. Machine harvesting may be
successful with other types, especially where the peppers are intended for
processing.

STORAGE  

Sweet
Peppers
: Store sweet peppers at 45°F to 55°F and 90% to 95% relative
humidity. Sweet, or bell, peppers are subject to chilling injury at
temperatures below 45°F, and temperatures above 55°F encourage ripening and
spread of bacterial soft rot. Bell peppers should not be stored longer than 2
to 3 weeks even under the most favorable conditions. At 32°F to 36°F peppers
usually develop pitting in a few days. Peppers held below 45°F long enough to
cause serious chilling injury also develop numerous lesions of Alternaria
rot. Alternaria causes the calyx to mold and decay. Holding at 40°F and
below predisposes peppers to Botrytis decay also.

Rapid
precooling of harvested sweet peppers is essential in reducing marketing
losses, and this can be done by forced-air cooling, hydrocooling or vacuum
cooling. Properly vented cartons are recommended to facilitate forced-air
cooling. If hydrocooling is used, care should be taken to prevent the
development of decay.

Sweet
peppers prepackaged in moisture-retentive films, such as perforated
polyethylene, have a storage life at 45°F to 50°F up to a week longer than
non-packaged peppers. The use of film crate liners can help in reducing
moisture loss from the fruit.

It is
commercial practice to wax fresh-market peppers. Only a thin coating should be
applied. Waxing provides some surface lubrication, which not only reduces
chafing in transit but also reduces shrinkage; the result is longer storage and
shelf life. Senescence of sweet peppers is hastened by ethylene. Therefore, it
is not a good practice to store peppers with apples, pears, tomatoes, or other
ethylene producing fruits in the same room.

Low-oxygen
(3% to 5%) atmospheres retard ripening and respiration during transit and
storage. High concentrations of carbon dioxide delay the loss of green color.
However, high carbon dioxide also causes calyx discoloration.

Dried
Chili and Other Hot Peppers
:

Storage
temperature depends on use; see text. A humidity of 60% to 70% is recommended.
Chili peppers are usually picked when ripe and are then dried and allowed to
equalize in moisture content in covered piles. Water is usually added to the
peppers after drying to reduce brittleness. They are then packed tightly into
sacks holding 200 or more pounds and are generally stored in non-refrigerated
warehouses for up to 6 months. The temperature of the warehouses depends to
some extent on their construction and the way in which they are managed but
chiefly on the outside temperature (50°F to 75°F). Insect infestation is a
major storage problem. In southern states, chili and other hot peppers are
dried, packaged, and then stored at 32°F to 50°F until shipped to processing
plants. Storage at low temperatures aids in retarding the loss of red color and
in slowing down insect activity.

The
moisture content of chili and other hot peppers when stored should be low
enough (10% to 15%) to prevent mold growth. A relative humidity of 60% to 70%
is desirable. With a higher moisture content the pods may be too pliable for
grinding and may have to be re-dried. With lower moisture content (under 10%)
pods may be so brittle that they shatter during handling; this causes losses
and the release of dust, which is irritating to the skin and respiratory
system.

The
use of polyethylene bags allows better storage and reduces the dust problem.
The liners ensure that the pods maintain a constant moisture content during
storage and up until the time of grinding; thus, they permit successful storage
or shipment under a wide range of relative humidities. Packed in this manner,
peppers can be stored 6 to 9 months at 32°F to 40°F.

Manufacturers
of chili and other hot pepper products hold part of their supply of the raw
material in cold storage at 32°F to 50°F, but they prefer to grind the peppers
as soon as possible and store them in the manufactured form in airtight
containers.

Freshly
harvested chili or other hot peppers should be stored under the same
temperature and humidity conditions as those for sweet peppers.

PACKAGING

Bell
peppers are packaged in 25 to 30-lb (l l/9 bushel) containers or 30-lb cartons.
Chili peppers and yellow types are packaged in 16 to 25-lb lugs or 10 to 20-lb
cartons.

image

Pepper harvest, courtesy of Planter’s Guild Inc.