Okra

Scientific Clarification

The following are the crop details for Okra:

Scientific name: Abelmoschus esculentus

Local names: Bamia, Binda (Swahili)

Order: Malvales

Family: Malvaceae

Genus: Abelmoschus




General Information

Okra, also known as lady's fingers, is mainly grown for its young immature pods, which are consumed as a vegetable, raw, cooked, or fried. It is a common ingredient in soups and sauces. The pods can be conserved by drying or pickling. The leaves are sometimes used as spinach or cattle feed, the fibers from the stem for cord, the plant mucilage (thick gluey substance) for medical and industrial purposes, and the seeds as a substitute for coffee. Okra seeds contain a considerable amount of good-quality oil and protein.

Okra plants have small erect stems that can be bristly or hairless with heart-shaped leaves. The leaves are 10–20 cm (4–8 in) long with 5–7 lobes The plant produces flowers with five white to yellow petals which are 4–8 cm (1.6–3.1 in) in diameter. The seed pod is a capsule up to 25 cm (10 in) long, containing numerous seeds. Okra can grow 1.2–1.8 m (4–6 ft) tall and as an annual plant, survives only one growing season.

It is believed to have originated in Ethiopia but is also particularly popular in India, West Africa, and Brazil.




Okra Varieties in Kenya

Pusa sawani: High-yielding variety tolerant to vein mosaic. It grows 2 to 2.5 m tall and has long pods. (18 to 20 cm), dark green, smooth, and has 5 ridges. Mainly for export.

Clemson spineless: 1.2 to 1.5 m tall. Pods are about 15 cm long, green, and moderately ridged.

Green Emerald2: This variety is about 1.5 m tall. Pods are 18 to 20 cm long, slightly ridged (rounded), and green.

White velvet: A medium-tall variety of 1.5 to 1.8 m high. Pods are 15 to 18 cm long, slender, tapered, smooth, and creamy white.

Dwarf Green Long Pod: It grows up to 0.9 m high. It has several side branches. The pods are angular and green and about 18 to 20 cm long.




Okra Varieties in India

Pusa Makhmali: Variety produces light green fruits.

Punjab no. 13: Suitable for cultivating in the spring-summer season. Fruits are light green, 5-ridged and of medium length.

Punjab Padmini: Fruits are quick growing, dark green, hairy, 5-ridged, and remain tender for a longer period. Matures within 55-60 days after sowing.

Parbhani Kranti: Fruits are medium-long with tender smooth surfaces at the marketable stage. Fruits have a good keeping quality. The average yield is 8.5-11.5 t/ha in 120 days.

Arka Anamika: Fruits are borne in two flushes. During the first flush, the fruits are borne on the main stem 45-50 days after sowing. During the second flush, the fruits are borne on short branches, which sprout from the middle portion of the main stem. Fruits are spineless with 5-6 ridges, delicate aroma, and good keeping quality.




Climatic Conditions, Soils, and Water Management

Okra is grown at elevations ranging from sea level to 1600 m. The optimum temperatures for the growth and production of high-quality pods range between 24 and 30°C. The crop is sensitive to frost and temperatures below 12°C.

Okra will grow on a wide range of soils, but it prefers soils high in organic matter. The seeds perform well on fertile, well-drained loamy soil. When the soil fertility level is low, organic manure, fertilizer, or compost can be applied to improve soil productivity. it must be frequently fertilized in sandy soils, as soluble nutrients readily leach from the root zone. Its optimum range of soil pH is between 5.8 and 6.5. A soil test will indicate if lime is required to adjust the pH and the amount to apply. If lime is recommended, dolomite should be used and applied 3 to 4 months before the crop is seeded. Okra is sensitive to salinity. Okra can grow in a wide range of rainfall regimes but needs 400 mm of water for the growing period of about 3 months. 




Uses

Okra is mainly consumed as a vegetable and it provides health benefits such as; strengthening bones, lowers blood pressure, prevents constipation and maintains healthy skin.




Planting procedure

Land preparation

Thorough soil preparation 2 to 3 months before planting is recommended to allow crop residues and organic matter in the soil to decompose before okra is planted. Early land preparation also permits weed seeds to germinate and allows early cultivation to destroy young weeds before planting.

Soil management

The crop produces reasonably well on most soil types, although a fertile loam is preferable. Cultivars that are susceptible to root-knot eelworm (Meloidogyne incognita) do not produce a satisfactory crop on infected light or sandy soils. This species tolerates soils that are slightly acidic and will grow successfully in soils with a pH of 6.0-6.8.

Sowing

Okra plants may be established by direct seeding in the field, by growing seedlings in nursery seedbeds, or by raising seedlings in plastic trays. Before planting, it is advisable to soak the okra seeds in water for 24 hours,  to break seed dormancy and speed up the germination rate or reduce germination days. In Kenya, okra is sown directly in the field. About 8 to 10 kg of seed is required per hectare. The planting depth is about 1.5 cm.

Spacing varies from 45 x 45 cm, 50 x 30 cm, or 60 x 15 cm between the rows and within the rows, respectively. In some parts of Kenya, okra is planted 2 x 2 m in flood irrigation basins. Spacing of about 1 to 2 feet intra-row and 3 to 4 feet inter-row should be used. The main export season in Kenya is October to May; hence planting should start in July to target this export season. However, with irrigation okra can be grown all year round for the local and off-season export markets.




Field Operations

  1. Fertilizer application

Before planting, manure or artificial fertilizer has to be mixed well into the top 10 cm of the soil. The uptake of minerals is rather high. When the crop yields 10 t of fresh fruits per hectare, the uptake is 100 kg N, 10 kg P, 60 kg K, 80 kg Ca, and 40 kg Mg. Fertilizer can be given in three split applications, at sowing, after 3 weeks, and again at 6 weeks after sowing.

The general recommendation in Kenya (issued by Horticultural Crops Development Authority) for conventional production (non-organic production) is as follows: well-composted manure should be applied at planting at the rate of 15 to 20 t/ha (17 to 20 gm/plant). It should be mixed thoroughly with the soil in the planting hole.

  1. Weeding

Okra is harvested over a long period and weed control is important throughout the cropping season. Smallholder growers in Kenya control weeds by hand hoeing.

  1. Rotation

Okra should be rotated with baby corn, maize, peas, onions, potatoes, fodder grass, or small grains. Being in the same family as cotton it shares the same complex of pests and diseases therefore okra should not be grown before or after cotton.

  1. Irrigation

Okra is a heavily foliaged crop, so its water requirements are high. According to the Kenya Ministry of Agriculture, okra needs 400 mm of water during the growing season of three months. A general guideline for semi-arid areas, where okra is mostly grown in Kenya, is to provide about 35 mm of water per week (this equals 35 liters of water per square meter). Critical times for irrigating okra are at emergence and from flowering to pod production. Saline or chlorinated water should not be used for irrigation.




Harvesting

Early-maturing cultivars give the first harvest 7 weeks after sowing. A developing fruit should be harvested 7-8 days after flowering. Earlier picking depresses yields because of suboptimal fruit weight. Delayed picking depresses marketable yields because over-aged fruits become fibrous. Therefore, okra fields are harvested at intervals of 2-3 days. For seed production, the whole crop can be harvested at once. As the plant continues to flower, fruits can be picked every 2 days. Picking fruits is usually done manually. Intensive contact with slightly hairy fruits and plants may lead to skin irritation.

Most varieties grown in Kenya are ready to pick 45 to 55 days after planting. Pods are ready for harvesting about 4 to 6 days after flowering. Pods are harvested when still tender and on attaining a length of 7 to 15 cm, depending on variety and market requirements.

Regular picking every 1 to 2 days is essential to ensure pods are within the size prescribed by the market. Okra should not be harvested when it is raining or excessively wet. Excess moisture can induce mold development on the pods and the cut petioles. Okra pods decay quickly; therefore they should be harvested within a day to market.

Harvesting is done by hand. The pods can be snapped off or cut off, leaving a small stalk not longer than one cm. The pods must be handled carefully otherwise they may be bruised and may discolor. It is best to pick pods into a waist bag to reduce skin damage and to avoid excessive bending of the pods. Wearing rubber gloves when harvesting and handling pods is recommended. This will protect the skin from irritating sap produced by the okra plant.




Postharvest Treatment

After harvesting, the fruits can be stored for only 3-5 days at about 10°C; lower temperatures may cause damage to the fruits. Okra should not be washed until shortly before use as washing makes the fruit slimy.

Fresh okra can quite easily be transported in bulk and kept for several days without much loss of quality. Dried okra is an important product in West Africa. Some countries have a small canning and freezing industry.




References

Aguair, J. L., McGiffin, M., Natwick, E. & Takele, E. (2011). Okra production in California. UC Vegetable Research and Information Center. Available at: http://anrcatalog.ucdavis.edu/pdf/7210.pdf. [Accessed 24 January 2023].

CABI Crop Protection Compendium. (2008). Abelmoschus esculentus (okra) datasheet. Available at: http://www.cabi.org/cpc/datasheet/1950. [Accessed 24 January 2023].

https://nhb.gov.in/pdf/vegetable/okra/okr011.pdf




Common Pests and Diseases

Diseases

Category : Fungal

Charcoal rot Macrophomina phaseolina

Symptoms
Discoloration of stem at soil line; cankers on stem may spread upwards; leaves may wilt and drop from plant; numerous small black sclerota (fungal fruiting bodies) develop in affected tissues and can be used to diagnose the disease
Cause
Fungus
Comments
Fungus had a wide host range and affects beans, tobacco, soybean, pigeon pea and many other crops; disease is primarily spread via microsclerota in the soil
Management
Rotate crop to non-host to reduce build-up of inoculum in the soil; avoid water stress to plants by irrigating when required

Fusarium wilt Fusarium oxysporum

Symptoms
Wilting of cotyledons and seedling leaves; cotyledons become chlorotic at the edges and then necrotic; older plants exhibit symptoms of wilting and leaf chlorosis; wilting is usually gradual but may be pronounced after heavy summer rain; if infection is severe plants become stunted and may be killed; vascular system of infected plants becomes discolored and can be seen by cutting the stem
Cause
Fungus
Comments
Disease emergence is favored by warm temperatures; fungus may be introduced to field through infected seed or by contaminated equipment and human movement
Management
Use on certified, disease-free seed; plant varieties with higher resistance to the disease in areas with a history of Fusarium diseases; fumigating the soil may reduce disease incidence

Powdery mildew Oidium asteris-punicei

Symptoms
Powdery white covering on leaves; patches may coalesce to cover entire plant; if plant is heavily infected leaves may roll upward and appear scorched
Cause
Fungus
Comments
Fungus overwinters on plant debris or alternate host; disease emergence is favored by warm, dry weather with cool nights that result in dew formation
Management
Use overhead irrigation (washes fungus from leaves and reduces viability); plant crop as early as possible; applications of appropriate fungicides may be necessary to control the disease

Southern blight Sclerotium rolfsii

Symptoms
Sudden wilting of leaves; yellowing foliage; browning stem above and below soil; browning branches; stem may be covered with fan-like mycelial mat
Cause
Fungus
Comments
Fungus can survive in soil for long periods; disease emergence favored by high temperatures, high humidity and acidic soil; disease found mainly in tropical and subtropical regions, including the southern United States
Management
Remove infected plants; avoid overcrowding plants to promote air circulation; rotate crops with less susceptible plants; plow crop debris deep into soil; provide a barrier to infection by wrapping lower stems of plant with aluminum foil covering below ground portion of stem and 2-3 in above soil line

White mold Sclerotinia sclerotum

Symptoms
Flowers covered in white, cottony fungal growth; small, circular, dark green, water-soaked lesions on pods leaves and branches which enlarge and become slimy; cottony white growth may be visible on lesions during periods of high humidity; death of branches and/or entire plant
Cause
Fungus
Comments
Fungus can survive in soil for in excess of 5 years; disease can be spread by wind, contaminated irrigation water and by infected seeds
Management
Rotate crops with non-hosts like cereals and corn; plant rows parallel to direction of prevailing winds to prevent spread of disease from secondary hosts nearby; avoid excessive nitrogen fertilizer; use a wide row spacing

Category : Viral

Enation leaf curl disease Okra Enation Leaf Curl Virus (OELCV)

Symptoms
On lower surface of leaves we will see a small pin head enations. This enation become warty and rough in structure at later stage. Reduce in leaf size. The stem, lateral branches and leaf petioles become twisted along enation. Leaves appear thick and leathery. In severely infected plants the emerging leaves shows bold enations and curling. And produce few deformed fruits.
Cause
Virus
Comments
The virus is transmitted by white fly.
Management
1. Remove the infected plant and burn them to avoid further spread of disease 2. Use yellow sticky traps to monitor whiteflies population 3. If the whiteflies infestation is more spray suitable insecticides.

Yellow Vein Mosaic Disease Bhendi Yellow Vein Virus (BYVMV)

Symptoms
The infected leaves shows alternate patches of green and yellow. Veins become clear and chlorotic. With the progress of disease the veins become conspicuous and both vein and vein lets become thick. In advance stage the stems and leaf stalk become distorted. Fruits are yellowish green in color and small in size.
Cause
Virus
Comments
Transmitted by white fly Bemisia tabaci. It causes huge loss if disease occur at early stage of crop.
Management
Use resistant cultivars. Sow disease free certified seeds. Roughing of infected plants. Follow crop rotation. Keep the field free from weeds. Control vector with suitable insecticides.

Pests

Category : Insects

Aphids (Green peach aphid, Potato aphid, etc.) Myzus persicae
Macrosiphum euphorbiae

Symptoms
Small soft bodied insects on underside of leaves and/or stems of plant; usually green or yellow in color, but may be pink, brown, red or black depending on species and host plant; if aphid infestation is heavy it may cause leaves to yellow and/or distorted, necrotic spots on leaves and/or stunted shoots; aphids secrete a sticky, sugary substance called honeydew which encourages the growth of sooty mold on the plants
Cause
Insects
Comments
Distinguishing features include the presence of cornicles (tubular structures) which project backwards from the body of the aphid; will generally not move very quickly when disturbed
Management
If aphid population is limited to just a few leaves or shoots then the infestation can be pruned out to provide control; check transplants for aphids before planting; use tolerant varieties if available; reflective mulches such as silver colored plastic can deter aphids from feeding on plants; sturdy plants can be sprayed with a strong jet of water to knock aphids from leaves; insecticides are generally only required to treat aphids if the infestation is very high - plants generally tolerate low and medium level infestation; insecticidal soaps or oils such as neem or canola oil are usually the best method of control; always check the labels of the products for specific usage guidelines prior to use

Armyworms (Beet armyworm, Western striped armyworm) Spodoptera exigua
Spodoptera praefica

Symptoms
Singular, or closely grouped circular to irregularly shaped holes in foliage; heavy feeding by young larvae leads to skeletonized leaves; shallow, dry wounds on fruit; egg clusters of 50-150 eggs may be present on the leaves; egg clusters are covered in a whitish scale which gives the cluster a cottony or fuzzy appearance; young larvae are pale green to yellow in color while older larvae are generally darker green with a dark and light line running along the side of their body and a pink or yellow underside
Cause
Insect
Comments
Insect can go through 3–5 generations a year
Management
Organic methods of controlling armyworms include biological control by natural enemies which parasitize the larvae and the application of Bacillus thuringiensis; there are chemicals available for commercial control but many that are available for the home garden do not provide adequate control of the larvae

Corn earworm Helicoverpa zea

Symptoms
Larvae damage leaves, buds, flowers and pods; young caterpillars are cream-white in color with a black head and black hairs; older larvae may be yellow-green to almost black in color with fine white lines along their body and black spots at the base of hairs; eggs are laid singly on both upper and lower leaf surfaces and are initially creamy white but develop a brown-red ring after 24 hours and darken prior to hatching
Cause
Insect
Comments
Adult insect is a pale green to tan, medium sized moth; insect is also very damaging pests of corn; insect overwinters as pupae in the soil
Management
Monitor plants for eggs and young larvae and also natural enemies that could be damaged by chemicals; Bacillus thuringiensis or Entrust SC may be applied to control insects on organically grown plants; appropriate chemical treatment may be required for control in commercial plantations

Cucumber beetles (Western striped cucumber beetle, Western spotted cucumber beetle, Banded cucumber beetle) Acalymma vittata
Diabrotica undecimpunctata
Diabrotica balteata

Symptoms
Stunted seedling; damaged leaves, stems and/or petioles; reduced plant stand; plants may exhibit symptoms of bacterial wilt; scars on fruit caused by beetle feeding damage; adult beetles are brightly colored with either a green-yellow background and black spots or alternating black and yellow stripes
Cause
Insect
Comments
Beetles overwinter in soil and leaf litter and emerge from soil when temperatures begin to reach and exceed 12.7°C (55°F)
Management
Monitor new planting regularly for signs of beetle; floating row covers can be used to protect the plants from damage but will need to be removed at bloom to allow bees to pollinate plants; applications of kaolin clay can be effective for management of small beetle populations; application of appropriate insecticides may be necessary

Loopers (Cabbage looper) Trichoplusia ni

Symptoms
Large or small holes in leaves; damage often extensive; caterpillars are pale green with a white lines running down either side of their body; caterpillars are easily distinguished by the way they arch their body when moving; eggs are laid singly, usually on the lower leaf surface close to the leaf margin, and are white or pale green in color
Cause
Insect
Comments
Insects overwinter as pupae in crop debris in soil; adult insect id a dark colored moth; caterpillars have a wide host range
Management
Looper populations are usually held in check by natural enemies; if they do become problematic larvae can be hand-picked from the plants; an organically acceptable control method is the application of Bacillus thuringiensis which effectively kills younger larvae; chemical sprays may damage populations of natural enemies and should and should be selected carefully

Thrips (Melon thrips) Thrips palmi

Symptoms
If population is high leaves may be distorted; leaves are covered in coarse stippling and may appear silvery; leaves speckled with black feces; insect is small (1.5 mm) and slender and best viewed using a hand lens; adult thrips are pale yellow to light brown and the nymphs are smaller and lighter in color
Cause
Insect
Comments
Thrips can produce several generations of insect per year
Management
Avoid planting next to onions, garlic or cereals where very large numbers of thrips can build up; use reflective mulches early in growing season to deter thrips; apply appropriate insecticide if thrips become problematic

Category : Nematodes

Root-knot nematode Meloidogyne spp.

Symptoms
Galls on roots which can be up to 3.3 cm (1 in) in diameter but are usually smaller; reduction in plant vigor; yellowing plants which wilt in hot weather
Cause
Nematode
Comments
Galls can appear as quickly as a month prior to planting; nematodes prefer sandy soils and damage in areas of field or garden with this type of soil is most likely
Management
Plant resistant varieties if nematodes are known to be present in the soil ;check roots of plants mid-season or sooner if symptoms indicate nematodes; solarizing soil can reduce nematode populations in the soil and levels of inoculum of many other pathogens

Category : Mites

Spider mites (Two-spotted spider mite) Tetranychus urticae

Symptoms
Leaves stippled with yellow; leaves may appear bronzed; webbing covering leaves; mites may be visible as tiny moving dots on the webs or underside of leaves, best viewed using a hand lens; usually not spotted until there are visible symptoms on the plant; leaves turn yellow and may drop from plant
Cause
Arachnid
Comments
Spider mites thrive in dusty conditions; water-stressed plants are more susceptible to attack
Management
In the home garden, spraying plants with a strong jet of water can help reduce buildup of spider mite populations; if mites become problematic apply insecticidal soap to plants; certain chemical insecticides may actually increase mite populations by killing off natural enemies and promoting mite reproduction
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