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Knowledge Base

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Introduction and History

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The Plant and Its Morphology

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Utilization

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Production Constraints

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Research Materials

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Major Peanut Producing Countries

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Terminologies

Introduction and History

The peanut (Arachis hypogaea), better known worldwide as groundnut and to lesser extent as earthnut, monkeynut, and goobers is not a true nut but rather an annual legume much like the bean or a pea (Nwokolo 1996). The peanut plant is unusual because it flowers above ground and pods containing one to five seeds are produced underground. Its seeds are rich source of edible oils and contain 40 -50% fat, 20 - 50 % protein, and 10 to 20 % carbohydrate. The seeds are nutritious and contain vitamin E, niacin, folacin, calcium, phosphorus, magnesium, zinc, iron, riboflavin, thiamine, potassium etc. Peanuts, peanut oil and peanut protein meals constitute an important segment of world trade in oilseeds and products. Peanut is the fifth most important oilseed in the world. Peanut is used for different purposes: food (raw, roasted or boiled, cooking oil), animal feed (pressings, seeds, green material, straw), and industrial raw material.

Origin

The archaeological records supports its cultivation between 300 and 2500 BC in Peruvian desert oases (Weiss 2000, Smith 2002). Although no archaeological evidence of peanuts has been uncovered in the area due its tropical climate, the Gurarani region of Paraguay, eastern Bolivia, and central Bolivia showed the greatest diversity of wild varieties of Arachis species. The cultivated peanut was likely first domesticated in the valleys of the Paraguay and Prarana rivers in the Chaco region of South America (Fig 1). The plant is believed to have been originally domesticated by predecessors of the Arawak- speaking peoples who now live in its homeland.

Fig 1: Centers of origin and diversity
(Source: Weiss 2000)

The first written account of the crop is found with the Spanish entry into Hispanola in 1502, where the Arawak cultivated under the name of mani (Sauer 1993). Records from Brazil around 1550 showed the crop was known there with the name mandubi. Early Spanish and Portuguese accounts record the presence of crop through of the West Indies and South America.

Diffusion
Today groundnut is widely distributed and has adapted in various countries of the World. The most important countries for production are India, China, USA, West and Southern Africa, and Brazil.
The diffusion of crop can be traced along the varietal lines (fig 2). Peanut is usually divided into 4 varieties: 'Virginia', 'Peruvian', Spanish', and 'Valencia'.

Fig 2 peanut center of origin (solid line), area of intensive cultivation (dotted line) and areas of maximum Cultivation (shaded)
(Source: Weiss 2000)

Krapovickas (1969) provided a history of introduction of these different varieties since 1500. The Virginia variety was taken from the Antilles to Mexico soon after 1500 and then quickly introduced to West Africa. The variety was introduced to eastern North America from both the West Indies and West Africa in the 17th century.
The Peruvian variety was taken to the Philippines by Spanish galleons and from there to southeastern China before 1600, where it was known as 'foreign beans'. It spread from there throughout China and from there to Japan where it was known as Chinese beans'. Chinese settlers were probably responsible for introduction to the rest of Southeast Asia and Indonesia. Peanuts arrived in India most likely from Africa as one of the plant's Indian names was "Mozambique bean".
The 'Spanish' was almost certainly taken from Brazil to Africa by Portuguese shortly after their contact with Brazil in 1500. There it mixed with 'Virginia' and produced the great diversity of African landraces. The 'Spanish' race was evidently introduced into Spain in the late 18th century, from Brazil via Lisbon. From Spain it was introduced to Southern France and finally to the USA in 1871. The Valencia was probably introduced to Spain from Cordoba, Argentina about 1900 and was introduced to USA from Valencia about 1910.
Peanuts did not reach England and France until long after Spanish and Portuguese had first encountered them. The first located use of the term peanut is found in the account of an Englishman's visit to the United States in 1794 (Smith 2002).

World Production

The peanut is one of the world's most popular and universal crops, cultivated in more than 100 countries in all six continents (Nwokolo 1996). China and India are the largest producers (Table 1). A substantial proportion of total production is consumed by growers, without ever being recorded (Weiss 2000). Although USA had been third largest producer in the world until mid - 1990s, Nigeria is the third largest producer in the world now. Israel ranks the top in yield per unit area with an average yield of 5,401 Kg/Ha in 2003. Figure 3 shows the groundnut production trend in the world since 1961. Fig 4 and 5 shows the percentage of groundnut production and area under cultivation in major groundnut producing countries in 2003 respectively.

Table 1. Groundnut Production, 2002

Countries

Production (Mt.)

Harvest area (Ha)

Yield (Kg/Ha)

  China

15,277,455

5,125,400

2,981

  India

7,500,000

8,000,000

938

  Nigeria

2,699,000

2,782,000

970

  United States of America

1,879,750

530,950

3,540

  Sudan

1,200,000

1,900,000

632

  Senegal

900,000

900,000

1,000

  Indonesia

803,000

646,000

1,243

  Myanmar

700,000

530,000

1,321

  Ghana

520,000

384,000

1,354

  Chad

450,000

480,000

938

  Viet Nam

400,100

245,000

1,633

  Congo, Dem Republic of

355,180

456,590

778

  Burkina Faso

323,642

342,637

945

  Argentina

314,300

155,000

2,028

  Cameroon

290,000

205,000

1,415

  Mali

257,108

314,856

817

  Guinea

252,000

210,000

1,200

  Egypt

207,000

64,000

3,234

  Brazil

172,031

82,481

2,086

  Zimbabwe

165,000

260,000

635

World

37,057,652

26,416,717

1403

Fig 3. World groundnut production trend (Source FAO 2003)

Fig 4 Percentage of groundnut production in major groundnut producing countries

Fig 5 Percentage of groundnut cultivation area by major groundnut producing countries

References

Kaprovickas, A. 1969. The Origin, Variability, and Spread of the Groundnut (Arachis hypogaea). In The Domestication and Exploitation of Plants and Animals. P.J. Ucko and J.W. Dimbleby, eds. Pp. 427-441. Chicago: Aldine.

Nwokolo, E. 1996 Peanut (Arachis hypogaea L.). In Food and Fee from Legumes and Oilseeds. E. Nwokolo and J. Smartt, eds. Pp. 49-63. New York: Chapman and Hall.

Smith, A.F. 2002 Peanuts: The Illustrious History of the Goober Pea. Chicago: University of Illinois Press.

Weiss, E.A. 2000 Oilseed Crops. London: Blackwell Science.

Contributed by Govinda Basnet

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The Plant and how it grows

Vegetative growth

The peanut Arachis hypogaea is an annual legume, unusual in its genus being polyploid (4x=40). It can interbreed only with another species A. monticola, the probable wild progenitor of the crop (Sauer 1993). The cultivated peanut plant is an erect or prostrate, usually 15 to 60 cm tall (fig1). It is sparsely hairy and, and has a well developed tap root system with many lateral roots. Roots are usually devoid of hairs, and a distinct epidermis. A unique characteristic of the peanut plant is the nyctinastic movements of the leaflets (Coffelt 1989). The leaf blade consists of four oval to obvate leaflets attached to the midrib by small articulations which allow for movement. During dark periods and hot sunny days, the paired leaflets are close together in a vertical position, and on a normal day leaflets are separated from each other in a horizontal position.

Fig 1. The Peanut plant
(Source: Kokalis-Burelle et al. 1997)

Flowers

Flowers are born on inflorescence located in the axils of the leaves. Flowers are never at the same node as vegetative branches, although very short internodes on some plants may make it appear that they are (Coffelt 1989). Environmental conditions may cause the transformation of reproductive axes into vegetative axes, but not the reverse. The first flowers appear from 4 to 6 weeks after planting. Each flower is subtended by two bracts; the lower, on an axis of the inflorescence and the upper in the axil of the lower bract (fig 2). The flower contains five petals: a standard, two wings, and two petals fused to form a keel. There are two calyx lobes, an awnlike one opposite the keel and a broad opposite the back of the standard. The flower has 10 stamens, two of which are usually not fully developed. The pistil consists of an ovary, style, and stigma. Anthesis and pollination usually occur at sunrise with pollination taking place within the closed keel of the flower.

Fig 2. peanut flower
(Source: Coffelt 1989)

The mature pod is indehiscent legume containing one to five seeds, enclosed in papery testas (fig 3). The seeds do not contain an endosperm but have two large cotyledons, an epicotyl with three meristems, a hypocotyls, and a primary root.

Varieties

The genus Arachis hypogaea has been divided into 4 different varieties as 'Virginia', 'Peruvian', 'Valencia', and 'Spanish'. These different types are believed to have thought to have originated in different locations. Virginia variety may have been developed in Amazonia. The Peruvian variety is the common type found in archaeological sites in the oases of Peru is believed to have been developed in Peru. The Spanish variety was grown by the peoples of northeastern Brazil. The Valencia variety may have been developed by the Guarani peoples of the Paraguay-Praraná basin.

The table below summarizes these varieties (Kokalis-Burelle et al 1997)

Subspecies
Cultivar

Primary area of origin

hypogaea

Virginia

Southern Bolivia and northern Argentina

hirsuta

Peruvian runner

Peru

fastigiata

Valencia

PeruBrazil and Paraguay

vulgaris

Spanish

Paraguay, Uruguay, and Brazil

The subspecies hypogaea and hirsuta share similar morphological features as they don't have floral axes on main axis (Weiss 2000, Bunting et al 1985). Pairs of vegetative branches and floral axes alternate along lateral branches. The Virginia type is less hairy and branches are short, whereas Peruvian is more hairy with long branches.

Similarly, the subspecies fastigiata and vulgaris share similar morphological features as floral axes are found on the main axis. There is continuous runs of multifloral axes along lateral branches. Valencia type is little branched whereas Spanish type is more branched.

The Virginia and Peruvian varieties are prostrate, have seed dormancy, and require 5 to 10 months growing season. The prostrate varieties are commonly called as runners as lateral branches remain close to the ground, giving spreading appearance. The Valencia and Spanish varieties are erect, have non dormant seeds, and mature in 3 to 5 months. Erect types are also called as bunchy type as the upright growth of branches give mature plant a tightly bunched, bushy appearance. Erect types often have lower individual nut yields per plant than prostrate types. However, erect types tend to have slightly higher seed oil and seed protein contents. Spanish variety is particularly rich in oil.

Ecology
The main range of peanut cultivation is between 35o S and 40o N, but it extends to 45oN in Central Asia and North America. It adapts to wide range of environments. It is normally grown commercially below 1250 m, although many varieties could be found at much higher elevations (Weiss 2000).

It is a day neutral plant and thus little affected by day length. However, plant growth is adversely affected by low light intensity. Bunchy types are generally more severely affected by climatic variation than runner types. Temperature between 25 to 30oC is optimum for plant development (Weiss 2000).

Once established, peanut is drought resistant, and to some extent it also tolerates flooding. A rainfall of 500 to 1000 mm will allow commercial production, although crop can be produced on as little as 300 to 400 mm of rainfall. Once pods are mature, rainfall will adversely affect the crop as some cultivars have a very brief dormancy and germinate under suitable condition.

References

Bunting, A.H., R.W. Gibbons, and J.C. Wynne. 1985 Groundnut (Arachis Hypogaea L.). In Grain Legume Crops. R.J. Summerfield and E.H. Roberts, eds. Pp. 747-800. London: Collins.

Coffelt, T.A. 1989 Peanut. In Oil Crops of the World: Their Breeding and Utilization. G. Robbelen, R.K. Downey, and A. Ashri, eds. Pp. 319-338. New York: McGraw-Hill Publishing Company.

Kokalis- Burelle, N., et al., eds. 1997 Compendium of Peanut Diseases. St. Paul, Minnesota: The American Phytopathological Society.

Weiss, E.A. 2000 Oilseed Crops. London: Blackwell Science.

Contributed by Govinda Basnet

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Polythene Mulching

Polythene mulching in groundnut has been attributed as one of the major improved cultivation practices for enhanced productivity in China. Because of its contribution in increasing groundnut production in China, polythene mulching is called as the “White Revolution”. Polythene mulching was introduced in China in 1978 from Japan. Polythene mulching has been found to be effective not only in increasing the yield but also in increasing seed oil content, protein content, and the level of eight essential amino acids. In China, the polythene mulching was found to increase yield between 18 to 49% depending on soil fertility conditions (Shufen 1998).

When grown under polythene mulch system, groundnut is sown approximately 10 days earlier and it matures about 10 days earlier than under non-mulched condition. With the polythene mulching groundnut producing areas could be extended to the northern cooler region. Polythene mulching increases the soil temperature by retaining the heat from the sun. The increased accumulated temperature shortens the crop period. During the hot season it also protects the soil from direct sunlight. Its impermeability to hot air ensures optimum temperature for the middle growth phase of groundnut (Shufen et al 1998). It also helps in retaining soil moisture by preventing evaporation loss of soil moisture. Besides these, polythene mulching helps in improving soil texture, increase in soil microorganisms activity and microclimate. Polythene mulch also prevents late set pegs from penetrating the soil thus saving nutrients for earlier set pods. Polythene mulching has been found effective in controlling weeds.

There are also some disadvantages of using polythene mulching. All the polythene film used in mulching cannot be retrieved, thereby causing environmental pollution. Residual film in the soil may interfere with the root development of the next crop. Sowing with polythene mulch takes much more time, labor and the cost of cultivation. It has also been found that seeds produced under polythene mulch condition are less viable.

Although polythene film of 0.004 to 0.014 mm thickness can be used, a thickness of 0.007 mm is optimum and more economical. The thinner (less than 0.005 mm) film does not well maintain the soil temperature and moisture and does not stop late set pegs from penetrating the soil. A film of light transmittance of more than 70 percent is optimum.

Reference

Shufen, Duan, Hu Wenguang, and Sui Qingwei. 1998. Groundnut in China: A Success Story. Bangkok: Asia Pacific Association of Agricultural Research Institutions.

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Peanut uses

History of use

The early records on peanut states that mani was a common food to the Indians of South America before the arrival of Columbus and other Spanish explorers. It was consumed as raw or roasted. It was also considered of having soporific, and anti inflammatory effect (Smith 2002). In Peru and Brazil it was used to prepare peanut milk and products similar to traditional almond confectionary. It was taken by Portuguese to Africa where it became an important part of diet. The peanut paste was used to thicken soups, stews and similar dishes, and the oil was used for culinary purposes.

Before 1800, in the Caribbean and in the British colonies in North America slaves grew peanuts on small garden. Peanuts were used to feed slaves almost from the earliest days of the European slave trade. White colonists do not appear to have consumed peanuts directly, but they used peanut to fatten swine and poultry (smith 2002). Early records of peanut use in the US shows that it was used as beverage as a good substitute for chocolate. Throughout the nineteenth century, peanuts were mainly sold roasted in their shells.

Utilization of Products

All parts of the peanut plant can be easily utilized. The vines with leaves make an excellent high protein hay for horses and ruminant livestock. The shells or pods can be used as feed for livestock, burned for fuel, made into particle board, and many other uses. The peanut is grown mainly for human consumption of the seed. The seed can be used directly for food and crushing to produce oil and a high protein meal. Nearly two thirds of all groundnuts produced are crushed for oil (Bunting et al 1985). Peanut oil can be used in cooking, lighting, fuel and as a food constituent. Peanut oil has a better keeping quality than soybean, corn, and safflower oils and is a good source of Vitamin E. Used directly as food, peanut is a major crop for subsistence (Hammons 1982). The multiples uses of the peanut make it an excellent cash crops for domestic markets as well as foreign trade.

In most parts of the world the peanut is utilized primarily as whole seeds. The most common method of preparation for human consumption of whole seeds is dry roasting the seed (Coffelt 1989). The peanut is well-established snack food as fresh cooked and roasted peanuts. In the USA, the major use of peanut is for grinding into peanut butter.

Peanut is also used as peanut flour, concentrates, and isolates. These serve as potential extenders in many meat formulations. Peanut flour has been used to replace part or all of wheat flour or corn meal in making various types of breads and other bakery products. Peanut protein isolates have for many years been used in the manufacture of imitation milk as an extender to cow or buffalo milk. Peanut protein isolate and peanut oil have been used to make cheese analogs for the production of cream cheese and cheese spread products.

Nutritional Quality

It is estimated that the shell represents about 25% of the dry weight of unshell peanut, and the kernel comprises 75%. Cotyledons are the main storage tissues and are a concentrated source of protein, lipids, and dietary energy. Amino acid profile of raw peanut is in many respects inferior to the profile of raw soybean. Comparatively, the protein content of raw peanut is only about 70% of that of raw soybean. Peanuts and peanut protein products are low in Sulfur based amino acids. Peanuts are a reasonable source of dietary minerals especially potassium, phosphorus, and magnesium. However, they are poor source of fat soluble vitamins like A, D, and K.

Peanut oil is an excellent source of mono- and polyunsaturated fatty acids, exceeding the levels of these fatty acids in soybean and corn oil, but significantly lower than in sunflower and safflower oil. Peanut oil contains about 1 % palmitic acid and 80 % oleic and linoleic acid (Nwokolo 1996).

Antinutritional Factors

Raw peanuts have some antinutritional factors like trypsin inhibitors, various lectins. They have very low concentrations of most of the antinutritional factors found in raw soybean. A goiterogenic factor has also been isolated and identified in the testa of the peanut. Some saponin-like compounds which are bitter tasting have been identified in the germ. The suggested atherogenic property of peanut is considered an antinutritional effect. Removal of peanut skins is usually one of the initial steps in further processing of peanuts.

Aflatoxins in Peanuts

In warm climates, grains are easily infected with toxigenic microorganisms. The best known toxic compounds of peanut are the aflatoxins, metabolic by-products of the moulds Aspergillus flavus and Aspergillus parasiticus. There are four types of aflatoxin, B1, B2, G1, and G2. Of these four, aflatoxin B1 is the most toxic and best known because it is a very potent hepatocarcinogen (Nwokolo 1996).

Although aflatoxin contamination of peanuts occurs during postharvest curing and storage, the most significant contamination usually occurs prior to harvest during periods of late season drought stress as peanuts are maturing. Mould infection of badly harvested and or poorly stored peanuts occurs around 20 to 25 oC. When these mouldy peanuts are eaten or processed into food or feed, aflatoxin poisoning occurs. Aflatoxin is a major problem in many tropical countries Increasing water stress during crop growth increases aflatoxin contamination in peanut. The toxins from the peanuts can be removed by extraction using polar solvents to which have been added 0.5% hydrogen peroxide or 0.2% sodium hypochlorite.

Recipes

Hundreds of culinary uses have been developed and patented for peanut. Following are some links to the various peanut recipes.
http://www.aboutpeanuts.com/reci.html
http://www.peanut-institute.org/recipes.html
http://aggie-horticulture.tamu.edu/plantanswers/recipes/peanutrecipes.html
http://southernfood.about.com/library/weekly/aa041397.htm

References

Bunting, A.H., R.W. Gibbons, and J.C. Wynne. 1985 Groundnut (Arachis Hypogaea L.). In Grain Legume Crops. R.J. Summerfield and E.H. Roberts, eds. Pp. 747-800. London: Collins.

Coffelt, T.A. 1989 Peanut. In Oil Crops of the World: Their Breeding and Utilization. G. Robbelen, R.K. Downey, and A. Ashri, eds. Pp. 319-338. New York: McGraw-Hill Publishing Company.

Hammons, R.O. 1982 Origin and Early History of the Peanut. In Peanut Science and Technology. H.E. Pattee and C.T. Young, eds. Pp. 1-20. Yoakum, Tex.: American peanut Research and Education Society, Inc.

Nwokolo, E. 1996 Peanut (Arachis Hypogaea L.). In Food and Fee from Legumes and Oilseeds. E. Nwokolo and J. Smartt, eds. Pp. 49-63. New York: Chapman and Hall.

Smith, A.F. 2002 Peanuts: The Illustrious History of the Goober Pea. Chicago: University of Illinois Press.

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Pests and Diseases

Peanut production process, from planting to storage, is affected by different types of stresses. These stresses are caused both by biotic and abiotic agents. Biotic agents include insects, fungi, bacteria, virus, nematodes, weeds and abiotic factors include physiological and environmental stresses.

Different parts of the plant are susceptible to different types of stresses. The peanut seed is affected by soil borne pathogens, preharvest and post harvest insects, and environmental conditions. During the early stages of growth roots are susceptible to infection several soil borne pathogen. Aboveground, the crown area of the plant stem is subject to attack by insects and various soil microorganisms. The list below provides an example of various agents that harm the peanut crop.

The basic idea to develop a successful crop management strategy is to provide an environment that allows maximum yield with reduced risks of crop loss, proper use of pesticides, and minimal environmental contamination. A successful health management must include management of: physiological and environmental disorders, weeds, preharvest and postharvest insects, viral diseases, bacterial diseases, foliar pathogens, soil borne fungal pathogens and nematodes, and mycotoxins producing fungi.

Insects pests

Insect pests damage almost every part of the peanut plant. Following is the list of insects causing damage to peanut.

Insect

Latin Name

Damage

Foliage feeders

Groundnut leaf miner

Aproaerema modicella

feeds between the epidermal layers of the leaf

Rednecked peanutworm

Stegasta bosqueella

feeds exclusively within a developing terminal

Corn earworm

Helicoverpa zea

consumes terminal, young foliage, and immature pegs

Army worms

Spodoptera spp

larvae feeds on the underside of leaflets, terminals

Bollworm, earworm

Helicoverpa zea

larvae feed on flowers and pods

Velvet bean caterpillar

Anticarsia gemmatalis

larvae feed on terminal and young foliage

Hairy caterpillars

Amsacta spp

larvae move and feed en masse on the underside of leaves

Intracellular feeders

Leafhoppers

Empoasca spp

adults and nymphs feed on the undersides of leaves by inserting mouthparts.

Tobacco thrips

Franklineilla fusca, Thrips palmi, Scirtothrips dorsalis

feed in leafbuds and flowers

Groundnut aphid

Aphis craccivora

adults and nymphs feed on leafbuds and unfurling leaves

Twospotted spider mite

Tetranychus urticae

adult injures plant by inserting the piercing mouth parts into plant cells and sucking the contents.

White flies

Bemicia tabaci

remove photosynthates directly from the phloem

Root and pod feeders

Lesser Cornstalk borer

Elasmopalpus lignosellus

larvae feed on roots and developing pods

Southern corn rootworm

Diabortica undecimpunctata howardi

adult beetles feed on leaves, and larvae feed on below ground.

White grub

Species of Lachnosterna, Adoretus, Anomala, Leucophilis

larvae feed on the taproots

Termites

Species of Odontotermes, Microtermes

damage pods by scarifying the pod, and by feeding on the seed

Wireowrm

Species of Conoderus

damage all underground parts

Millipeds

Peridontopyge spp

feed on seedling plants, and developing pods

Stored-product feeders

Indianmeal moth

Plodia interpunctella

larvae feed on shelled seeds, or seeds on damaged or cracked pods

Rice moth

Corcyra cephalonica

larvae feed loose shelled seed or on seed in cracked pods

Flour beetles

Tribolium castaneum, T.confusum

adults and larvae feed on the surface of the seed and burrow into the seed

Groundnut bruchid

caryedon serratus

attacks unshelled, undamaged pods

Pod sucking bug

Elasmolomus sordidus

adult pierces a pod with mouth parts and feeds on the oil.

Diseases

Fungal Disease and Causal Agents
Anthracnose Colletotrichum mangenoti, C. arachidis, and C.dematium
Aspergillus crown rot aspergillus niger, A. pulverulentus
Alternaria leaf spot Alternaria arachidis
Black hull Thielaviopsis basicola
Botrytis blight Botrytis cinerea
Charcoal rot Macrophomina phaseolina
Cylindrocladium black rot Cylindrodium crotalariae
Diplodia collar rot Diplodia gossypina
Early leaf spots Cercospora archidicola
Late leaf spots cercosporidium personatum
Fusarium wilt Fusarium spp.
Melanosis Stemphylium botryosum
Foot rot Neocosmospora vasinfecta
Peanut pod rot Pythium myriotylum, Rhizoctonia solani, Fusarium solani
Powdery mildew Oidium arachidis
Verticillium wilt Verticillium dahliae
Sclerotinia blight Sclerotinia minor
Stem rot Sclerotium rolfsii
Rust Puccinia arachidis
Web blotch Phoma arachidicola
Yellow mold and aflatoxin Aspergillus flavus, A. parasiticus

Diseases caused by Bacteria and causal agents
Bacterial leaf spot Pseudomonas spp
Bacterial wilt Pseudomonas solanacearum

Diseases caused by virus and vectors
Tomato spotted wilt and peanut bud necrosis, Frankliniella fusca, F. Occidentalis, Thrips palmi
Peanut clump, Polymixa graminis
Groundnut rosette Aphis craccivora
Peanut mottle Aphis craccivora, A. gossypii, Myzus persicae, Hyperomyzus lactucae, Rhopalosiphum padi, R. maidis
Peanut stripe, Aphids
Peanut stunt, Aphis cracciovra, A. spiraecola, and Myzus persicae
Cowpea mild mottle Bemicia tabaci
Peanut chlorotic streak Aphis craccivora, Myzus persicae, Bemisia tabaci

Diseases caused by Nematodes
Root knot nematodes Meloidogyne spp
Root lesion nematodes Pratylenchus brachyurus
Sting nematodes Belonolaimus spp
Ring nematodes Criconemella ornate
Peanut pod nematodes Ditylenchus africanus

Abiotic diseases
Drought stress
Frost injury
Genetic disorders
Hail injury
Herbicidal injury
Lightning injury
Nutrient imbalances, Ozone damage

Weeds
The ten most common weeds in peanut are:
Nutsedge Cyperus spp
Morning glory Ipomoea spp
Pigweed Aamranthus spp
Crabgrass Digitaria spp
Teaxas Panicum Panicum texanum
Cocklebur Xanthium strumarium
Florida beggarweed Desmodium tortuosum
Prickly sida Sida spinosa
Sicklepod Cassia obtusifolia
Goosegrass Elusine indica

Parasitic flowering plants
Alectra vogelli is a root parasite
Striga spp. general parasite
Cuscutta campestris is a stem parasite

References
Kokalis-Burelle, N. et al. (eds.)
1997 Compendium of peanut diseases. St. Paul, Minnesota: APS Press
Melouk, Hassan and Shokes, Frederick (eds.)
1995 Peanut Health Management. St. Paul, Minnesota: APS Press

Web Resources
"Peanut Disease Atlas" website maintained by Thomas A. Lee, Jr., C. Wendell Horne and Mark C. Black (last accessed on January 2, 2004)

Contributed by Govinda Basnet

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Pops in the Peanut

Pops is the condition of occurrence of unfilled or partially filled pods with shriveled kernels. It has been found to be caused by calcium deficiency in the soil. Apparently, different growth stages like vegetative growth, nodulation, pod setting seems normal and the occurrence of pops becomes apparent only during shelling. The occurrence of pops in groundnut was first observed in 1885 by Jones who reported that unless the soil contains a good percentage of lime in some form in an available state no land will produce a crop of pods, although it may yield large luxuriant vines (Syamasonta 1990).

The problems of pops become severe in heavily leached soils which have low pH, usually in high rainfall areas. Pops are more area specific than season specific. The conditions are favorable for pops when the calcium levels reach below 1.0 milliequivalent Ca. Pops may also be caused by unfavorable conditions such as drought during pod filling. Even if there is enough calcium lack of moisture during pod filling stage results in pops.

This problem is common in Zambia, Zimbabwe, and Malawi. Different types of peanut differ in their response to Ca application. For example bunchy types generally give a slower response to Ca than runner types. It is common in Virginia types in Rusape area of Zimbabwe, northern region of Malawi, and northern and north-western provinces of Zambia.

References

Syamasonta, M.B. 1990 A Review of 'Pops' Research in Zambia. Fourth Regional Groundnut Workshop for Southern Africa, Arusha, Tanzania, 1990, pp. 17-21. ICRISAT.

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Research Materials

F.K. Tsigbey . R. L. Brandenburg , and V. A. Clottey. 2003. Peanut Production Methods in Northern Ghana and Some Disease Perspectives.
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Terminologies

aflatoxin

Chemical by-product from Aspergillus flavus and A. parasiticus harmful to humans and other animals.

bunching

A clustering or tufting growth and appearance. Spanish types have upright bunch. In the valencia type braches grow outwards then upwards giving appearance of curved open bunch.

gynopophore

A stalk bearing the fertilized female organ of a flower, also known as peg

haulm

Stem or stalks

inchic

The name with which peanut was called by Incas

kuli-kuli

A popular Nigerian peanut snack made by deep frying peanut cakes.

mandubi

The name with which peanut was described in early records in Brazil

mani

The name with which peanut was reported in early written records especially in Spanish. The common name for peanut in Spain and Spanish America, except Mexico

peg

A stalk bearing the fertilized female organ of a flower, also known as gynophore.

peruvian

A peanut variety under subspecies hypogaea. Botanically, it is A. hypogaea subsp. hypogaea var. hirsuta

pops

A condition wherein the pods are unfilled or partially filled with shriveled kernels. This is caused by Calcium deficiency in soil.

rosette

Disease symptom characterized by short, bunchy growth habit resulting from shortened internodes but no comparable reduction in leaf size.

runner

Peanut plant habit where branches grow horizontally on the surface. All runner types are alternately branched. Runners have become popular after the introduction of high yielding runner variety, the Florunner. They have attractive kernel size range, and are used mostly for peanut butter.

spanish

Peanut variety under subspecies fastigiata. Botanically, it is A. hypogaea subsp. fastigiata var. vulgaris. They have smaller kernels, with reddish brown coat. They are used mostly in peanut candy, and have higher oil content.

spreading

A type of peanut plant habit where the plant is recumbent with numerous creeping laterals. It has a scattering or diffusing, extending growth and appearance.

testa

The skin or coat of a seed

valencia

A peanut variety under subspecies fastigiata. Botanically, it is A. hypogaea subsp. fastigiata var. fastigiata. Usually have three or more kernels per pod, are very sweet, mostly roasted and sold in the shell.

virginia

Peanut variety under subspecies hypogaea. Botanically, it is A. hypogaea subsp. hypogaea var. hypogaea. They have alternating branches, seed dormancy. They have the largest kernels, account for most of the peanuts roasted and eaten as in shells.

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