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Capsicum annuum and C. frutescens
Last revised February 12, 2010
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. A simple key to identifying the five domesticated species of Capsicum may be found on page 1996 of "Peppers of the World--an Identification Guide" by Dave DeWitt and Paul W. Bosland, Ten Speed Press, PO Box 7123, Berkeley, CA 97407.
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 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.
Pacific Northwest 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 (see appropriate sections below).
See the Vegetable Variety Selection Resources page to find varieties that have been shown to perform well in the Pacific NW.
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.
HOT PEPPERS AND PUNGENCY RATINGS
The most common sensory method to determine pungency in peppers has been an organoleptic test (Scoville, a dilution-taste procedure) with results expressed as Scoville Heat Units (SHU). The validity and accuracy of it have been widely criticized. The American Spice Trade Association and the International Organization for Standardization have adopted a modified version. The American Society for Testing and Materials is considering other organoleptic tests (the Gillett method) and a number of chemical tests to assay for capsaicinoids involved in pungency. Still, the values obtained by the various tests are often related to Scoville Heat Units. For more information on chile peppers, see The Chile Pepper Institute.
Category, type of fruit attachment and pungency range: Variety name Color Stages Pungency Remarks -------------------------------------------------------------------------- Bell, 3.5"X4.5", fruit pendant, pungency 0-100 Scoville Heat Units (SHU) Bell King green to red sweet early Bell Captain green to red sweet thick walls Bell Tower green to red sweet smooth Bellboy green to red sweet thick wall Bellestar green to red sweet smooth Bonanza green to red sweet vigorous Calif. Wonder 300 green to red sweet late, thick Cardinal green to red sweet thick wall Cubico green to red sweet Four Corners green to red sweet good shape Jupiter green to red sweet large, mid Lady Bell green to red sweet early Mayata green to red sweet v.lg. fruit Midway green to red sweet early Mission Belle green to red sweet v. smooth Parks Early Thickset green to red sweet early Parks Whopper green to red sweet med. Pip green to red sweet large Predi green to red sweet lg. 4-lobe stuffer Ringer green to red sweet large, mid Skipper green to red sweet smooth Sweet Belle green to red sweet mid Goldie yellow to red sweet early Gypsy yellow to red sweet early Yellow Belle yellow to red sweet early Admiral green to yellow sweet blocky Early Bountiful green to yellow sweet Golden Summer green to yellow sweet thick wall Golden Cal. Wonder green to yellow sweet thick wall Golden Bell green to yellow sweet early Inia green to yellow sweet thick wall Klondike Bell green to yellow sweet early, thick wall Orobelle green to yellow sweet thick wall Summer Sweet 820 green to yellow sweet Golden Crest gr to orng-yellow sweet Quadrato d'Oro gr to orng-yellow sweet Ariane green to orange sweet large, thick Corona green to orange sweet large, thick Kerala green to orange sweet large, thick Oriole green to orange sweet large, thick Salsa RZ green to orange sweet large, thick Super Stuff yellow to orange sweet early Valencia yellow to orange sweet early, thick Wonderbelle yellow to orange sweet Lorelei purple then red sweet small Purple Beauty purple then red sweet small Purple Belle purple then red sweet small Violetta purple then red sweet small Blue Jay gr-lavender to red sweet Islander gr-lavender to red sweet Lilac gr-lavender to red sweet Chocolate Bell gr to chocolate sweet large fruit Mulato gr to chocolate sweet Sweet Chocolate gr to chocolate sweet small fruit Albino gr to white to red sweet small Dove gr to white to red sweet small Ivory gr to white to red sweet Elongated Bell; (lamuyo type fruit) 3.5"x5"; pendant, pungency 0-100 SHU: Blue Star green to red sweet large, late Elisa green to red sweet mid Marengo green to yellow sweet Melody green to red sweet early Signet green to yellow sweet early Anaheim; fruit 2"x7"; pendant, pungency 500-3,500 SHU (most 500-1000 SHU): Anaheim TMR light green to red mild Anaheim M light green to red warm Coronado light green to red warm New Mexico 64L light green to red mild NuMex Conquistador light green to red sweet for paprika Volcano light green to red hot Poblano/ancho; fruit heart-shaped 3"-4" x 4"-7"; pendant, 1,000-2,000 SHU. The poblano pepper is a major type grown in Mexico, used green, red or dried (called ancho when dried). It is commonly used for chiles rellenos: Ancho 101 dark green to red mild thick wall Esmeralda dark green to red mild thick wall New Mexican dark green to red mild thick wall Poblano dark green to red warm thick wall Verdano dark green to red warm thick wall Elongated, tapered; fruit variable shapes and sizes; pendant, 0-1000 SHU: Banana Supreme green to yellow sweet early Canape green to yellow sweet early Cuban yel-grn:red orange warm Cubanelle yel-grn:red orange mild long fruit Hungarian Wax grnish yel:yellow warm Sweet Banana grnish yel:yellow sweet Cherry; about 1" diameter; upright, 100-5,000 SHU: Cascabel green to red hot Large Red Cherry green to red warm Sweet Cherry green to red warm Cayenne; fruit 0.5"x3"; pendant, 30,000-50,000 SHU. A favorite in Creole and Cajun cooking: Large Red Thick green to bright red fiery slender Long Slim green to bright red fiery slender Carolina Cayenne green to bright red fiery Charlston Hot grn to orange to red fiery to 4" long Super Cayenne grn to bright red fiery long slender Jalapeño; fruit 1.5"x3"; pendant, 2,500-5000 SHU. The most common hot chili grown in the U.S.A.: Jalapa green to red hot blunt cylind. Jalapeño M green to red very hot thick wall Jalapeño Hot green to red hot smooth Mitla hybrid green to red hot thick, blunt cyl. Tam Jalapeño #1 green to red hot thick wall Others Pepperoncini; fruit 1"x2"; pendant, 200-500 SHU: Pepperoncini pale grn to yel mild twisted, wrinkled Pepperoncini Italian pale grn to yel mild Pepperoncini Greek Golden yellow mild Pepperoncini is used primarily for pickling and is harvested at the green to yellow stage, before full maturity. Information from trials in Louisiana (Louisiana Coop. Ext. Service Publ. 2433) suggests 12 to 18-inch spacing between plants, 70 days planting to harvest. It is harvested with stems attached and has a harvest interval of 2-3 days. Yields are 4,000 to 6,000 lb/acre. A skilled worker can harvest 25-30 lb/hour. Over a 60-90 day harvest period, the labor requirement to harvest an acre would be about 240 hours. Pimento; fruit 1.5"x2.5"; pendant, 0-100 SHU: Pimento L green to red sweet thick wall Serrano; fruit 0.5"x2.25"; pendant, 5,000-10,000 SHU: Serrano types dark green to red very hot small Tabasco C. frutescens; fruit 0.25"x 1.25";pendant, 30,000-50,000 SHU: Tabasco yel-orange to red fiery small Habanero (C. chinense) a fiery-hot, box-shaped small pepper turning from green to orange, red, yellow or white when ripe. Although the Habanero pepper has been listed as being the hottest of all peppers, some rated at 200,000 to 300,000 SHU, not all Habaneros are hot! Hot Habanero peppers are used to make hot bottled sauces. They are grown mainly in Central America and Yucatan. Other extremely hot C. chinense peppers include Scotch Bonnet (yellow), and Bahamian. Novelty, ornamental: Marbles (prolific round, mix of green, yellow and red fruit) Riot (prolific upright long fruit, mix of green, yellow and red).
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 caneberries 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 Western Oregon. 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 1/2 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.
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:65-85 F. Nights: 60-65 F. Temperatures above 95 F may result in flower bud drop. Highest yields are obtained when soil temperatures remain in the 70-75 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.
A few peppers are grown in greenhouses. The varieties Bellboy, Blue Star and Mogador 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 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 1/2 pint of 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 are sown October through February for harvest of red fruit approximately 5 months later, March through July.
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.
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 especially for production in western Oregon. 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 (GA) is labelled for promotion of pepper plant growth in all states but California. The label calls for application of 1 or 2 sprays of 1-3 g ai/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 labelled for increased fruit set and fruit growth. Apply 1 or two sprays of 1-3 g ai/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 under Pacific Northwest environmental conditions.
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.
A total of 12-15 inches may be needed in western Oregon and 25-30 inches in eastern Oregon, depending on planting date and harvest season. Approximate summer irrigation needs for the Hermiston area have been found to be: 3.5 inches in May, 5.0 in June, 7.5 in July, and 7.0 in August.
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.
In the Northwest, 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 (Quoted or modified from USDA Ag. Handbook 66 and other sources)
Store sweet peppers at 45 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 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 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 but this is uncommon in Oregon. 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 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 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 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 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.
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.
Fresh Market Vegetable Production, Peppers