Green gram (Vigna radiata) belonging to the Fabaceae family is an annual leguminous crop which is grown for its seeds, which are a high source of nutrients.
The crop is easy to cultivate and can grow up to a height of 30-120cm, producing pods.
Dried seeds are cooked or milled into flour, while the crop residues are used as fodder or in making green manure.
VARIETIES
The two major varieties grown in Kenya are;
- KS20 (uncle) – matures in 80-90days, pods turn brown when dry while grains are dull green in colour and bigger in size compared to n26
- N26 (nylon) – matures in 60-65 days, pods are black when dry and grains are shiny green in colour.
ECOLOGICAL REQUIREMENTS
- Soils– green grams thrive in a well-drained soil, rich in nutrients and with an optimum PH of 6.0-7.5.
- Altitude– the crop grows best at an altitude of 0-1600M ASL.
- Temperature- an optimum temperature of between 28-30 degrees centigrade is fit for the growth of green grams. Extreme temperatures affect crop growth and development.
- Rainfall– green grams are relatively drought tolerant and can give reasonable yields with an annual rainfall of between 350-650mm. Too much rain or long dry spells are reduce yields. Excessive rainfall during flowering causes flower abortion while dry weather conditions are important during harvesting.
PLANTING
Propagation is by seeds. These seeds should be certified or disease free. Damaged or shriveled seeds should not be planted.
Before planting, land should be prepared to a fine tilth.
Seeds are planted at a spacing of 45*15cm, a depth of about 3-5cm.
An acre needs 4-6kg of green gram seeds.
Planting should be done at the onset of the rains if production is rain fed. Delayed sowing may cause crop failure or reduced yield.
Germination occurs within 5-7 days and this depend on the variety and environmental factors.
Green grams can be planted alone or intercropped with other crops like maize, sorghum, cowpeas, etc.
PEST & DISEASE MANAGEMENT
Pests
- Cutworms-these are brown or black caterpillars usually found in the soil, which cut the stem of younger plants below the soil surface. Heavy infestations can lead to total crop loss.
Dress seeds with SHIELD 600FS 3ml/kg
DRENCH soil with PROFILE 440EC 60ml/20l or PENTAGON 50EC 20ml/20l
- Aphids- these are soft bodied, green or black insect pests which suck plant sap. Infested leaves curl and crinkle and attack the pods as well. Aphids excrete honeydew as they feed, which encourages the development of sooty mold.
Spray KINGCODE ELITE 50EC 10ml/20l or LEXUS 247SC 8ml/20l or PENTAGON 50EC 10ml/20l
Spray JAMBO CLEAN 100ml/20l to clean the sooty mold.
- Pod sucking bugs– these include giant coreid bug, green stink bug, etc. they suck sap from the pods and seeds. This may cause necrosis, pod malformation, premature drying, formation of empty pods, shriveling of seeds, among others.
Spray EMERALD 200SL 10ml/20l or LOYALTY 700WDG 5g/20l or PRESENTO 200SP 5g/20l
- Pod borers– these include the African bollworm and they feed on leaves, flowers and pods. They bore holes on pods and feed on the seeds, with the heads inside the pods. These borers cause significant losses if not controlled.
Spray LEXUS 247SC 8ml/20l or KINGCODE ELITE 50EC 10ml/20l or BACIGUARD 16WD 15g/20l
- Whiteflies– these are white flying insect pests which suck plant sap and secrete honeydew as they feed which facilitates the development of sooty mold. Infested leaves curl, become distorted and eventually drop. They are also vectors of plant diseases.
Spray TAURUS 500SP 10g/20l or LEXUS 247SC 8ml/20l or PROFILE 440EC 30ml/20l
Spray JAMBO CLEAN 100ml/20l to clean the sooty mold.
- Foliage beetles- these feed on the leaves leading to defoliation, especially of the young plants.
Spray SINOPHATE 750SP 20g/20l or LEXUS 247SC 8ml/20l or KINGCODE ELITE 50EC 10ML/20L
- Thrips- these prefer mostly the flowers, although they also feed on leaves and petioles. Attacked flowers turn brown, dry and become distorted. This decreases pollination ability and seed set.
SPRAY ALONZE 50EC 5ml/20l or DEFENDER 25EW 40ml/20l or PROFILE 440EC 30ml/20l
- Bean flies– the larvae (small whitish maggots) tunnel through the main stem and feed, causing significant damages. In severe cases of infestations, Seedling may die, leaves of the older plants turn yellow and become stunted while stems get thicker than normal and crocked.
Do seed dressing with SHIELD 600FS 3ml/kg
Drench soil with EMERALD 200SL 20ml/20l or PROFILE 440EC 60ml/20l
Spray KINGCODE ELITE 50EC 10ml/20l or PENTAGON 50E 10ml/20l or LEXUS 247SC 8ml/20l to control the adults bean flies.
Diseases
- Damping off– infection causes rotting of seeds before they emerge as well as seedlings after emergence from the soil.
Drench soil with PYRAMID700WP 100g/20l or spray crop with CHANCETYL ELITE 800WDG 50g/20l
- Anthracnose– this attacks all the above ground parts of the crop but pods are mostly damaged, whereby they develop brown sunken lesions. These lesions are covered with pink spores under humid conditions. The seeds become brownish black.
Spray RANSOM 600WP 15g/20l or DUCASSE 250EW 20ml/20l or ABSOLUTE 375SC 10ml/20l
- Powdery mildew– infection causes development of white powdery patches on the leaves and other plant parts which gradually enlarge, covering the entire surface, as infection progresses. Severely infected parts turn yellow and are distorted, defoliation occurs.
Spray RANSON 600WP 15g/20l or DOMAIN 250EC 10ml/20l or BRADLEY 500SC 10ml/20l
- Bacterial blight-infection causes formation of small brown blotches on the leaves which enlarge as infection continues eventually causing the leaves to fall off and subsequent death of the plant.
Spray GREENCOP 500WP 50g/20l or COLONIZER 440WP 50g/20l or TRINITY GOLD 425WP 50g/20l
- Rust– on infection, the disease appears as reddish brown blisters which are found mainly on the underside of the leaves, on pods and stems. In severe cases, both sides of the leaves are covered with rust pustules and defoliation may follow, while pods shrivel.
Spray MILESTONE 250SC 10ml/20l or RANSOM 600WP 15g/20l or DUCASSE 250EW 20ml/20l
- Yellow mosaic– this is a viral disease which causes serious losses. It is transmitted by whiteflies. Infected leaves become necrotic, diseased plant are stunted, mature late and produce few flowers and pods. The pods are usually reduced in size and turn yellow.
Control vectors (whiteflies) by spraying TAURUS 500SP 10g/20l or PROFILE 440EC 30ml/20l
NUTRITION
The crop should be supplied with enough nutrients for optimal production. This can be achieved through application of basal and foliar fertilizers.
For instance;
- DAP should be applied during planting. Considering the amount of organic matter in the soil, manure can also be added.
- Top dressing should be done using CAN, about 4-5 weeks after germination
In order to improve on nutrient uptake by the plants, stimulate growth among other benefits, the basal fertilizer and/or manure should be mixed with HUMIPOWER at the rate of 1kg Humipower into 50kg basal fertilizer or 1 ton manure.
Some of the recommended foliar feeds include the following;
- OPTIMIZER 10ml/20l- this helps in managing plant stress, boosting its immunity, supplying both micro and macro nutrient elements, preventing flower abortion, among other benefit. It can be sprayed at any stage of the crop development.
- GOLDCHANCE SERIES 50g/20l – this helps in taking care of the plant while at the different stages of growth and development, which leads to increased yields.
- LAVENDER 20ml/20l– this is very important at early and vegetative stages of the plant growth.
WEED CONTROL
Weeds compete with the target crop for nutrients, water, space and sunlight, as well as harbouring pathogens. In order to reduce the losses attributed to weed infestation, green grams garden should be kept weed free.
When the crop begins flowering, weeding should be minimizes in order to prevent disturbances.
Before planting the crop, spraying weeds with CLAMPDOWN 480SL 200ml/20l reduces weed development greatly throughout the growing season.
NOTE; whenever doing any foliar spray, the product (insecticide, fungicide, foliar feed or herbicide) should be mixed with INTEGRA 3ml/20l. This is a sticker, spreader and penetrant, which improves the effectiveness of the product.
MATURITY, HARVESTING & STORAGE
Green grams mature within 60-90 days after sowing, depending on environmental factors as well as the variety.
Harvesting should be done when most of the pods have turned black. This is achieved through picking the individual pods or uprooting the entire plant.
Delayed harvesting results into shattering of the pods and other losses can occur, e.g. infestation by pests.
The harvested pods should be dried for about 2-3 days then threshed and winnowed, ready for consumption or storage.
Green grams are very susceptible to attack by brucchids and should therefore be stored soon after sun drying in airtight containers or gunny bags in a clean ventilated room. Seed treatment is recommended for a longer storage period.
NB;
- Proper drying of the green grams is highly required in order to prevent contamination with aflatoxins and development of pathogens.
- Infected seeds should not be mixed with the sound ones.
