D. H. Putnam1, E. S. Oplinger2, T. M. Teynor3, E. A. Oelke1, K. A. Kelling2, and J. D. Doll2

1Department of Agronomy and Plant Genetics, Minnesota Extension Service, University of Minnesota, St. Paul, MN 55108.
2Departments of Agronomy and Soil Science, College of Agricultural and Life Sciences and Cooperative Extension Service, University of Wisconsin-Madison, WI 53706.
3Center for Alternative Plant and Animal Products, University of Minnesota, St. Paul, MN 55108.
July 1991.

I. History:

The cultivated peanut or groundnut (Arachis hypogaea L.), originated in South America (Bolivia and adjoining countries) and is now grown throughout the tropical and warm temperate regions of the world. This crop was grown widely by native peoples of the New World at the time of European expansion in the sixteenth century and was subsequently taken to Europe, Africa, Asia, and the Pacific Islands. Peanut was introduced to the present southeastern United States during colonial times. Peanut was grown primarily as a garden crop in the United States until 1870. As a field crop, peanut was used commonly for hog pasture until about 1930.

Peanut, an important oil and food crop, is currently grown on approximately 42 million acres worldwide. It is the third major oilseed of the world next to soybean and cotton (FAO Food Outlook, 1990). India, China, and the United States have been the leading producers for over 25 years and grow about 70% of the world crop. Peanut was ranked ninth in acreage among major row crops in the United States during 1982 and second in dollar value per acre. Production of peanut in the U.S.A. during 1989-1990 was estimated at 1.8 million tons, or about 8% of the world production of 23.2 million tons (FAO Food Outlook, 1990). In 1983, Georgia, Texas, Alabama, and North Carolina grew 80% of the 1,375,000 acres of peanut in the United States. Virginia, Oklahoma, Florida, South Carolina, and New Mexico were the other states with more than 10,000 acres of peanut.

The peanut crop in the U.S.A. is composed of four market types from two subspecies. A. hypogaea hypogaea includes the Virginia and Runner market types. The second subspecies, A. hypogaea fastigiata, includes two botanical varieties of economic importance: vulgaris, the Spanish market type, and fastigiata, the Valencia market type. Virginia peanuts have the largest pods and elongated seeds, while Runner peanuts are medium-size varieties of the Virginia type. Spanish types have smaller round seeds and Valencia is intermediate in size and shape. Valencia is grown primarily in New Mexico, Spanish in Oklahoma and Texas, and other types in the Southeast and Texas. The Runner type includes 70% of the edible trade in the U.S.A. with Virginia and Spanish accounting for 20 and 10%, respectively. Valencia peanuts generally constitute less than 1% of the U.S. market (Knauft and Gorbet, 1989).

Peanut has only occasionally been grown in northern states due to its warm temperature requirement. Use of poorly adapted varieties and improper production practices usually resulted in low yields and poor quality nuts. However, peanut has good potential as a food crop in Minnesota and Wisconsin and could be an alternative cash crop to soybean, corn, potato, or fieldbean (Robinson, 1984, and Pendleton, 1977).

II. Uses:

All parts of the peanut plant can be used. The peanut, grown primarily for human consumption, has several uses as whole seeds or is processed to make peanut butter, oil, and other products. The seed contains 25 to 32% protein (average of 25% digestible protein) and 42 to 52% oil. A pound of peanuts is high in food energy and provides approximately the same energy value as 2 pounds of beef, 1.5 pounds of Cheddar cheese, 9 pints of milk, or 36 medium-size eggs (Woodroof, 1983).

Peanuts are consumed chiefly as roasted seeds or peanut butter in the United States compared to use as oil elsewhere in the world. Americans eat about 4 million pounds (unshelled weight) of peanuts each day. Approximately two-thirds of all U.S. peanuts are used for food products of which most are made into peanut butter. Salted and shelled peanuts, candy, and roasted-in-shell peanuts are the next most common uses for peanuts produced in this country. The remaining one-third of annual production is used for seed, feed, production of oil, or exported as food or oil. The large nuts sold as in- and out-of-shell are supplied by Virginia (confectionery or cocktail) and Runner ("beer nuts") types. Spanish varieties supply small shelled nuts, "redskins", and the Valencia type is used for medium-size nuts in the shell. Runner and Spanish are made into peanut butter while all types are used for peanut products that do not require a specific seed size.

Nonfood products such as soaps, medicines, cosmetics, and lubricants can be made from peanuts. The vines with leaves are an excellent high protein hay for horses and ruminant livestock. The pods or shells serve as high fiber roughage in livestock feed, fuel (fireplace "logs"), mulch, and are used in manufacturing particle board or fertilizer.

III. Growth Habits:

Peanut is a self-pollinating, indeterminate, annual, herbaceous legume. Natural cross pollination occurs at rates of less than 1% to greater than 6% due to atypical flowers or action of bees (Coffelt, 1989). The fruit is a pod with one to five seeds that develops underground within a needlelike structure called a peg, an elongated ovarian structure.

Peanut emergence is intermediate between the epigeal (hypocotyl elongates and cotyledons emerge above ground as in soybean) and hypogeal (cotyledons remain below ground as in fieldpea) types. The hypocotyl elongates but usually stops before cotyledons emerge. Leaves are alternate and pinnate with four leaflets (two pairs of leaflets per leaf). The peanut plant can be erect or prostrate (6 to 24 in. tall or more) with a well developed taproot and many lateral roots and nodules. Plants develop three major stems, i.e., two stems from the cotyledonary axillary buds equal in size to the central stem during early growth.

Bright yellow flowers with both male and female parts are located on inflorescences resembling spikes in the axils of leaves. One to several flowers may be present at each node and are usually more abundant at lower nodes. The first flowers appear at 4 to 6 weeks after planting and maximum flower production occurs 6 to 10 weeks after planting.

Eight to 14 days after pollination aerial pegs will grow 2 to 3 in. into the soil and then turn to a horizontal orientation to mature into a peanut pod. Pods reach maximum size after 2 to 3 weeks in the soil, maximum oil content in 6 to 7 weeks, and maximum protein content after 5 to 8 weeks. The peanut crop matures after 7 to 9 weeks in the soil, which is indicated by maximum levels of protein, oil, dry matter, and presence of darkened veining and brown splotching inside the pod. Peanuts usually require a minimum of 100 to 150 days from planting to maturity depending on the variety planted.

Flowering continues over a long period and pods are in all stages of development at harvest. Pegs will eventually rot in the soil (25% after 12 weeks in the soil) and the resulting loose pods are lost during the harvest. Since the pod wall is needed to protect the seed, as it is moved through the various markets from producer to processor or consumer, yields and farm prices are based on a pod rather than seed basis.

IV. Environment Requirements:

A. Climate:

Temperature is the major limiting factor for peanut yield in northern states since a minimum of 3,000 growing degree-days (with a base of 50o F) is required for proper growth and development (Robinson, 1984). A peanut crop will not reach optimum maturity for a marketable yield to justify commercial production in areas with fewer heat units during the growing season. This eliminates some of Minnesota and most of Wisconsin as practical production areas. Little if any growth and development occur at temperatures below 56o F (Emery et al., 1969) and 86o F is reported to be optimal (Ketring, 1984).

Rainfall distribution varies greatly from western Minnesota to south eastern Wisconsin and irrigation may be a yield-stabilizing factor. University of Minnesota studies over a six-year period indicated that irrigation of sandy soil increased average yield by 1,000 to 1,450 lb/acre. However, in some years it did not increase yields appreciably, and irrigation expenses and lower land values may give an economic advantage to dryland production over use of irrigation. Research in Ontario, Canada indicated that the most critical time to apply water was during the flowering period.

B. Soil:

Soil for peanut production should be a light-colored, light textured with good drainage, and moderately low amounts of organic matter. Such soil is preferred since it is usually loose and friable, permitting easier penetration of roots and pegs, better percolation of rainfall, and easier harvesting. Light-colored soils reduce staining of pods which ensures greater eye appeal when the crop is used for unshelled nuts. Well-drained soils provide proper aeration for the roots and nitrifying bacteria that are necessary for proper mineral nutrition of the plant. Medium to heavy soils or those with a high clay content should also be avoided due to excessive loss of pods when harvesting peanuts.

Organic matter should be maintained at a level of 1 to 2% to improve water-holding capacity of the soil and supply plant nutrients. Peanut grows best in slightly acidic soils with a pH of 6.0 to 6.5, but a range of 5.5 to 7.0 is acceptable. Saline soils are not suitable since peanut has a very low salt tolerance (Weiss, 1983).

C. Seed Preparation and Germination:

Poor stand is perhaps the most common cause of low yields. To obtain a full stand, use undamaged seed with intact seed coats and treat shelled seed with an approved seed protectant prior to planting. Planting seeds rather than pods allows for easier machine planting and more uniform stands. Robinson (1984) reported higher yields when seed was used because planting pods delayed emergence due to slower absorption of moisture into the shells.

V. Cultural Practices:

A. Seedbed Preparation:

Peanut should not be grown in the same fields for successive years, but should be produced in a crop rotation plan. Soil samples should be taken before pre-plant field preparation to determine nutrient needs. Fertilizer, if needed, may be broadcast prior to plowing. Plow 8 to 9 in. deep to completely cover plant residues, which reduces losses from stem- and peg-root diseases (Sclerotium rolfsii) and weeds. The operations necessary to produce a seedbed for corn or soybean are suitable for peanut.

B. Seeding Date:

Planting in early June was originally favored in Minnesota due to the warm temperature required for optimal growth of peanut. However, planting in early May gave higher yields, larger seeds, and higher shelling percentage (Table 1). Peanut planted in early May required 9 more days to emerge and had a slower development than a crop planted in June. However, the planting in early May flowered earlier which allowed more pods to reach maturity before frost.

Table 1. Yields of early-, medium-, and late-planted peanut on different soil types in Minnesota, 1981-19821.
Planting Dates Silt Loam Dryland Sand Irrigated Sand All 3 Soils (Avg.)
  -------------------- lb Pods/acre --------------------
April 29 – May 6 1290 1000 1840 1380
May 14 – May 21 1260 860 1540 1220
June 1 – June 2 1060 590 1170 940
1From R.G. Robinson (1984).

C. Method and Rate of Seeding:

Plant seeds on smooth, uniform, well-prepared seedbeds with planting equipment properly adjusted to prevent damage to the fragile seed. Seed that splits will not germinate and grow. The short plant height of Spanish varieties results in them not filling 30 in. rows, yet other varieties may fill them by midsummer. Spanish and Valencia varieties had greater yields with 18 in. row spacing than in 30 in. rows, except on dryland sand (Table 2). The narrow 18-inch row spacing is about minimum for tractor wheels when cultivating (due to crop damage and yield reduction), and 22 in. is often better. Peanut planted in narrow row spacing appears to result in greater yields, yet the row spacing used for planting will largely depend on the type of planting and harvesting equipment available.

Comparison of ridge- and level-planted peanut in Minnesota indicated that ridge planting resulted in earlier flowering by 1 to 2 days but had no other advantages. Ridge planting might be better for some harvesting machinery. A late hill-up cultivation showed no advantage over level cultivation. For once-over harvesting, researchers from Ontario, Canada recommend planting on level fields parallel to the direction of plowing in rows spaced 24 in. apart.

Planting rates should be expressed in seeds per acre rather than pounds per acre since varieties and seed lots vary greatly. The highest yields were produced in 18 in. rows planted with 105,000 seeds per acre while highest yields from 30 in. row spacing resulted from only 70,000 seeds per acre. Seventy-thousand seeds per acre produced highest yields on dryland sand where row spacing had no effect. A seeding rate of 90,000 seeds per acre is recommended in Minnesota and Wisconsin with adjustments for germination below 90%, soil texture, and seed price.

Seed should be planted 1 to 2 in. deep since at greater depths, slower and poorer emergence results. However, planting 2 to 4 in. deep to reach moisture in sandy soil is successful in late May or early June in Minnesota. Time to emergence varies with seed quality, and soil temperature, moisture, and texture. It is typical for peanut to have a slower emergence than soybean in Minnesota.

Table 2. Effects of different row spacings and soil types on yields of peanut in Minnesota, 1981-19821.
  Row Spacing (in.)
Soil Type 18 30
  ---------- lb Pods/acre ----------
Silt Loam 1580 1370
Dryland Sand 1210 1250
Irrigated Sand 1870 1680
1Data from R.G. Robinson (1984).

D. Fertility and Lime Requirements:

Peanut responds well to residual soil fertility from previous crops in the rotation, but usually has a low response to fertilizer in soils with medium to high fertility levels. When nutrients are needed (low or very low soil test levels) broadcast applications are recommended especially of potash due to the low salt tolerance of peanut. Rates should be similar to those used for soybean. Since it is a legume, peanut can biologically fix its own nitrogen. The adequacy of farm soils for fertility for peanut should be checked with soil tests. Optimum pH levels of 6.0 to 6.5 will usually result in adequate calcium being present, however on lighter soils especially where long term applications of potash have been made, Ca may be limiting pod formation. Soil test Ca should be above 600 to 800 ppm. Although plant analysis may be useful for micronutrient levels, it does not detect Ca shortages in storage organs such as peanut pods. The severe calcium and micronutrient deficiencies that occur in the major peanut production areas are not likely here. Nitrogen fertilizer or seed inoculation with the proper Rhizobium strain is needed for a crop on irrigated sandy soil (Table 3). One-hundred-fifty pounds of nitrogen per acre were required to equal the yield produced with seed inoculation alone. An alternative to seed inoculation is to place granular inoculants in the seed furrow with a planter attachment.

Table 3. Yield response of Valencia and Spanish peanut to rhizobial inoculation or nitrogen fertilizer on dryland and irrigated sandy soil in Minnesota, 19821.
Treatment Dryland Irrigated
  ------------ lb Pods/acre ------------
Untreated 570 930
Inoculation 490 1380
N, 50 lbs/acre, 6/2 610 1050
N, 150 lbs/acre (50 lbs. each on 6/2, 7/1, 7/28) 480 1390
1Data from R.G. Robinson (1984).

E. Variety Selection:

The variety selected will depend largely on soil type and length of growing season. The Spanish type will mature sooner (90 to 120 days) than Runner or Virginia types. Most Valencia varieties mature in 90 to 110 days while Runner and Virginia types require 130 to 150 days to reach maturity. Previous attempts to raise peanut in Minnesota and Wisconsin usually involved Spanish and occasionally Runner and Virginia varieties. Only early-maturing varieties of the Valencia type are grown commercially in Ontario, Canada.

Field trials in Minnesota and Wisconsin indicated that Valencia and Spanish varieties with shorter maturity were most promising (Tables 4 and 5). These types initiate pegs from leaf axils on the main stem, and consequently, some pods mature sooner than those of Virginia and Runner types that do not produce pegs on the main stem. Valencia varieties produced much cleaner pods than Spanish varieties that required washing after harvest, especially when grown in nonsandy soil.

Growers should also consider varieties developed in Ontario at the University of Guelph (i.e., OAC Garroy, OAC Tango, or OAC Ruby). Garroy is a red-seeded Valencia type with an erect plant habit that yields consistently higher than U.S. varieties. Ruby is a higher-yielding replacement for Garroy. Ontario varieties are usually planted at the same time as soybeans and should mature in 110 to 120 days. Seed for these varieties can be obtained from Department of Crop Science, University of Guelph, Guelph, Ontario N1G 2W1.

Table 4. Yields of peanut varieties in Minnesota on three soils, 1981-19831 .
Variety Market Type ------------ Soil Type ------------
    Silt Loam Dryland Sand Irrigated Sand
    ------------ lb Pods/acre ------------
Minnesota X52 Valencia-Spanish 1580 1320 1820
McRan Valencia 1540 1210 1700
Valencia C Valencia 1480 1250 1590
Pronto Spanish 1450 1210 1420
Valencia A Valencia 1490 1180 1370
Early Spanish Spanish 1260 1260 1000
Delhi Spanish 1200 1130 1100
NC 7 Virginia 540 390 410
Florunner Runner 480 330 390
1Data from R.G. Robinson (1984).

Table 5. Yield and agronomic characteristics of peanuts grown at Hancock, Wisconsin, 19761.
Variety Type Yield2 Shelling
Seed Weight
(Grams/100 Seeds)
1. Delhi Spanish 2770 64.3 30.5 16
2. A-114 Spanish 3100 66.3 28.5 12
3. Comet Spanish 2657 64.5 30.4 16
4. Trifspan Spanish 2746 67.6 30.6 12
5. Tamnut Spanish 2323 64.6 31.2 15
6. Valencia Valencia 2653 70.2 36.6 21
7. Tennessee Red Valencia 2536 69.8 37.1 21
Average 2684 66.7 32.1 16
LSD 0.05 4.8 3.6 2
1Data from Pendleton and Weis, (1977).Planted May 15; harvested October 7
2Pounds of dry pods/acre

F. Weed Control:

Weeds can lower yields significantly and make harvesting difficult. Peanut plants grow more slowly than soybeans and take almost three months to achieve a complete ground cover. As a result the combination of cultivation and herbicides is usually necessary. In major peanut production states, crop rotation is the first step in a sound weed management program. p>

1. Mechanical:

Cultivation requires the use of sweeps to skim just beneath the soil surface or use of carefully adjusted rotary gangs (rolling cultivator). Precise depth and lateral control of either cultivator is necessary to avoid making preemergence herbicide (if applied) ineffective or causing peanut injury with an accompanying reduction in yields and quality. Improper cultivation will damage plants and provide an entry point for disease organisms. Soil thrown on plants by cultivation will inhibit flower, peg, and pod development. When preemergence or preplant herbicides have not been used, mechanical weeding is possible prior to emergence of seedlings, which is usually about 7 days after planting. Two weeding operations are usually sufficient, the first performed at 14 to 20 days after planting. The second cultivation is dependent on weed growth, but it is not recommended to delay it later than 60 days after planting (1983, Weiss).

2. Chemical:

Many herbicides are registered for use in peanut. These include Balan (PPI), Basagran (POST), Blazer (POST), 2,4-DB (POST), Dual (PPI or PRE), alachlor (Lasso and other names) (PPI, PRE), POAST (POST), PROWL (PPI), and SONALAN (PPI). Tank mixes of several of these products can be applied to broaden the spectrum of weeds controlled. Consult the product label for information on rates, tank mixes, harvest intervals, etc.

G. Disease and Their Control:

Research plots in Minnesota or Wisconsin did not have serious injury from diseases. Leaf spot diseases were observed in August. Disease problems may appear with continued peanut production in northern states.

H. Insects and Other Predators and Their Control:

Injury from insects occurred rarely in Minnesota or Wisconsin research plots. Potato leafhopper was controlled in a few trials. Birds were a problem in eating peanut left in windrows to dry. Insects, nematodes, and diseases that are a problem to peanut production are controlled by crop rotation and/or pesticides in southern states.

I. Harvesting:

The optimum time for harvesting is when most pods have a veined surface, seed coats are colored, and 75% of pods show darkening on the inner surface of the hull. However, peanut does not reach this stage in Minnesota, so immature pods are removed in the threshing, drying, and cleaning operations. Harvesting in northern areas should begin after the first killing frost if soil moisture is at a level suitable for cultivation since wet soil sticks to pods.

Harvesting usually starts with clipping or coultering. Rotary mowers remove up to half of the top growth when plant growth is too great for efficient harvesting. A killing frost may make this step unnecessary, since most of the leaves may have already fallen off the plant. Varieties with prostrate growth may overlap between rows and a coulter makes the vertical cut between rows. The next operation frequently uses a digger-shaker-windrower. Dig deep enough to prevent cutting pegs. Windrow-inverting attachments orient plants as they leave the shaker so pods are primarily on the top of windrows to permit more air circulation and exposure to sunlight for a shorter drying time.

Windrowed peanut may be combined-harvested wet (35 to 50% moisture), semidry (18 to 25%), or dry (8 to 10%). These peanuts may reach the semidry condition (seeds rattle in pods) 1 to 3 days after digging. Drying in the windrow to a moisture level of 8 to 10% requires 5 to 10 days of good drying weather. However, peanut remaining in windrows for several days is more susceptible to weather damage than when freshly dug. Combining wet (green) or preferably semidry peanut, followed by artificial drying, may result in better quality nuts. Adjust combines regularly to give more picking action when vines are tough, and reduce picking action when vines are dry, to obtain good picking efficiency and minimize mechanical damage to peanut hulls.

White and Roy (1982) reported that a once-over harvester used for peanut variety Valencia gave 50% more total harvested yield than conventional digging and combining methods. Percentage of loose, shelled seeds was reduced from 10 to 1%, and subsequent germination improved from 45 to 86%. A once-over harvester developed in Canada had less than 3% loss and 1% mechanical damage while maintaining high viability of seed. Certain cultural practices were recommended to make once-over harvesting easier and more efficient than use of a digger-shaker-windrower.

J. Drying and Storage:

The two most important operations in handling peanut after harvest are cleaning and drying to a safe moisture content (5 to 10%). Pods should be kept dry and protected against infestation from insects or rodents, as well as from loss of natural color and flavor, and prevention of the development of off-flavors and rancidity. Artificial drying of wet or semidry peanut should start immediately after combining to prevent mold growth and aflatoxin formation. Presence of aflatoxin is a concern in peanut production states with warmer climates. However, cool September and October temperatures in Minnesota should minimize this problem when proper drying and storage practices are followed.

Unheated air may be used for drying when relative humidity is below 65%. Besides removal of water, drying causes physical and biochemical changes that can be harmful or beneficial to flavor and quality. Peanut seed should not be heated above 95o F to avoid off-flavors, and the drying rate should not exceed 0.5% per hour. Safe storage of peanut requires an atmosphere with low relative humidity (60 to 70%). Robinson (1984) reported that peanut maintains a moisture content of about 7% at a relative humidity of 65 to 70%. The National Peanut Council has published detailed information on the proper handling, storage, processing, and testing of peanuts.

Peanut saved for seed must be protected from insect pests and rodents as well as from high temperatures and high relative humidities (> 70%). Peanut is usually stored in the form of unshelled nuts. Seven to eight month storage is usually required for peanut used as seed, and those intended for food uses can be stored until the start of next harvesting season. Seed harvested from Minnesota research plots usually tested over 90% germination. Seed retained viability longer when stored in the pod than when shelled. Seed stored with 5% moisture content lost viability more slowly than seed with 8% moisture, but relative humidity must be less than 50% to maintain such a low moisture level. In a storage trial in Minnesota, shelled seed maintained viability for three years when kept frozen (32o F) and for one year in a heated (68o F) office.

Most seed sold to growers is treated with fungicides to prevent damage from seed-rotting and damping-off fungi in the soil. Germination and emergence of hand-shelled seed was also improved when treated with fungicides. Seed satisfactory for planting can be produced in Minnesota.

VI. Yield Potential and Performance Results:

Previous attempts to raise peanut in Minnesota and Wisconsin usually involved Spanish and occasionally Runner and Virginia varieties. Few of the many peanut varieties and introductions have been grown in the Upper Midwest, but field trials indicated that Valencia and Spanish types were most promising due to shorter crop times. Average yields in Minnesota trials ranged from 400 to 1800 lb/acre (Table 4) while a trial conducted in Wisconsin had yields ranging from 2300 to 3100 lb/acre. OAC Garroy, a Valencia-type variety, yielded 2400 lb/acre in Ontario, Canada. The varieties developed in Ontario should also be considered for use in Minnesota and Wisconsin.

VII. Economics of Production and Markets:

Peanut markets are well established and shortages of this protein-rich crop have occurred. Acreage allotments in the U.S.A. were discontinued in 1981 so anyone can grow peanut, but only previous growers were given allotments for quota-peanut poundage that are eligible for quota-peanut price support. Peanut production in the U.S. during 1982 was limited by legislation at 1,614,000 acres for quota-peanut price supports. Quota peanuts have a higher price support ($642.79/short ton or 32 cents/lb in 1990-1991) than non-quota or additional peanuts ($149.79/short ton or 7.5 cents/lb) whether grown by quota or non-quota producers.

Peanuts from new growers, the third category of production, can only be sold for export or crushed for oil at the additional peanut price (minimum of 7.5 cents/lb). Allotments for quota-peanut poundage would not apply for peanut grown in the Midwest. Higher prices on the world market would encourage production by new growers. However, the lower quality peanut produced due to a shorter growing season (lack of uniform maturity of a crop) would be used for oil and meal production, and realize a much lower return for the farmer. If commercial peanut production will be extended to the Upper Midwest, additional research is needed to develop varieties that are earlier maturing and require fewer heat units to produce a good crop. Peanut production in the Upper Midwest at this time is economically inefficient until earlier maturing varieties become available.

VIII. Information Sources:

A heat unit index for virginia-type peanuts. 1969. D.A. Emery, J.C. Wynne, and R.O. Hexem. Oleagineux 24:405-409.

A once-over peanut harvester. 1982. P.H. White, and R.C. Roy. Proc. Am. Peanut Res. Educ. Soc. 14(1):116.

Commercial peanut production in Ontario. 1989. N.W. Shiedow, R.C. Roy, and D.L. Van Hooren, AGDEX 143, Ontario Ministry of Agriculture and Food.

FAO (Food and Agricultural Organization of the United Nations) Food Outlook. 1990. Rome, Italy.

Genetic diversity among peanut cultivars. 1989. D.A. Knauft and D.W. Gorbet. Crop Science 29:1417-1422.

National Peanut Council. 1970. Voluntary code of good practices for purchasing, handling, storage, processing and testing if peanuts. 8th ed.

Oilseed crops. 1983. E.A. Weiss. Longman Inc., NY.

Peanut: A food crop for Minnesota. 1984. R.G. Robinson. University of Minnesota Agric. Expt. Sta. Bultn. AD-SB-2478.

Peanut. 1989. T.A. Coffelt. In: G. Robbelen, R.K. Downey, and A. Ashri (eds.), Oil Crops of the World - Their Breeding and Utilization McGraw-Hill,NY.

Peanuts in Wisconsin. 1977. J.W. Pendleton and G.G. Weis. UWEX Field Crops 32.0, University of Wisconsin - Madison, WI.

Peanuts, processing, products. 1983. J.G. Woodroof (ed.) Third edition. AVI Publishing, Connecticut.

Peanut science and technology. 1982. ed. by H.E. Patee and C.T. Young, American Peanut Research and Education Society, Inc., Texas.

Temperature effects on vegetative and reproductive development of peanut. 1984. D. L. Ketring. Crop Sci. 24:877-882.

The information given in this publication is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no endorsement for one product over other similar products is implied by the Minnesota and Wisconsin Extension Services.

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