Green gram (Vigna radiata), a member of the Fabaceae family, is an annual leguminous crop cultivated for its nutrient-rich seeds.

This crop is known for its ease of cultivation and can reach heights ranging from 30 to 120cm, producing pods.

The dried seeds of green gram are commonly used in cooking or ground into flour. Additionally, the crop residues have multiple uses, including as fodder for livestock or as a component in making green manure.

VARIETIES

In Kenya, the cultivation of green gram involves primarily two major varieties:

  1. KS20 (commonly known as “Uncle”): This variety matures in approximately 80 to 90 days. When fully dried, the pods of KS20 turn brown, while the grains are dull green in color. In comparison to the N26 variety, the grains of KS20 are larger in size.
  2. N26 (also referred to as “Nylon”): This variety has a shorter maturity period, typically maturing in about 60 to 65 days. When dried, the pods of N26 appear black, and the grains have a shiny green color.

These two varieties, KS20 and N26, are prominent choices for green gram cultivation in Kenya, each with distinct characteristics and different maturation periods.

ECOLOGICAL REQUIREMENTS

Soil: Green grams thrive in well-drained soils that are nutrient-rich, with an optimal pH range of 6.0 to 7.5.

Altitude: The crop performs best at altitudes ranging from sea level up to 1600 meters above sea level (ASL).

Temperature: Green grams prefer an optimum temperature range of 28 to 30 degrees Celsius for growth. Extreme temperatures, either too high or too low, can negatively impact the crop’s growth and development.

Rainfall: Green grams exhibit relatively good drought tolerance and can produce reasonable yields with an annual rainfall range of 350 to 650mm. However, excessive rainfall or extended dry spells can decrease yields. Excessive rainfall during the flowering stage can lead to flower abortion, while dry weather conditions are preferable during the harvesting period.

PLANTING

Green grams are propagated through the use of seeds, which should be certified or free from diseases. It is important to avoid planting damaged or shriveled seeds.

Before planting, the land should be prepared by ensuring it is finely tilled.

Seeds should be planted at a spacing of 45 by 15 centimeters, at a depth of approximately 3 to 5 centimeters.

For an acre of land, 4 to 6 kilograms of green gram seeds are typically required.

If relying on rainfall for irrigation, planting should be done at the onset of the rainy season. Delayed sowing may result in crop failure or reduced yield.

Germination of the seeds typically occurs within 5 to 7 days, although the timing can vary depending on the variety and environmental conditions.

Green grams can be grown as a standalone crop or intercropped with other crops such as maize, sorghum, or cowpeas, among others.

PEST & DISEASE MANAGEMENT

Pests

  1. Cutworms: These caterpillars are brown or black and are typically found in the soil. They cut the stems of young plants below the soil surface, which can result in total crop loss. To address cutworm infestations, dress the seeds with 3ml/kg of SHIELD 600FS. Additionally, drench the soil with 60ml/20l of PROFILE 440EC or 20ml/20l of PENTAGON 50EC.
  2. Aphids: Aphids are soft-bodied, green or black insect pests that suck plant sap. Infested leaves curl and crinkle, and they also attack the pods. Aphids excrete honeydew, which leads to the development of sooty mold. To control aphids, spray 10ml/20l of KINGCODE ELITE 50EC, LEXUS 247SC, or PENTAGON 50EC. To clean the sooty mold, spray 100ml/20l of JAMBO CLEAN.
  3. Pod sucking bugs: This category includes pests such as the giant coreid bug and green stink bug, which feed on sap from the pods and seeds. Their feeding can cause necrosis, pod malformation, premature drying, formation of empty pods, and shriveling of seeds. Use 10ml/20l of EMERALD 200SL, LOYALTY 700WDG, or PRESENTO 200SP to control pod sucking bugs.
  4. Pod borers: African bollworms are pod borers that feed on leaves, flowers, and pods. They bore holes in the pods and feed on the seeds, often with their heads inside the pods. Untreated pod borer infestations can lead to significant losses. Spray 8ml/20l of LEXUS 247SC, KINGCODE ELITE 50EC, or BACIGUARD 16WD to control pod borers.
  5. Whiteflies: Whiteflies are white, flying insect pests that suck plant sap and secrete honeydew, which facilitates the development of sooty mold. Infested leaves curl, become distorted, and eventually drop. Whiteflies can also transmit plant diseases. Control whiteflies by spraying 10g/20l of TAURUS 500SP, 8ml/20l of LEXUS 247SC, or 30ml/20l of PROFILE 440EC. Use JAMBO CLEAN (100ml/20l) to clean the sooty mold.
  6. Foliage beetles: Foliage beetles feed on leaves, especially of young plants, leading to defoliation. To address foliage beetle infestations, spray 20g/20l of SINOPHATE 750SP, 8ml/20l of LEXUS 247SC, or 10ml/20l of KINGCODE ELITE 50EC.
  7. Thrips: Thrips primarily target flowers but can also feed on leaves and petioles. Infested flowers turn brown, dry, and become distorted, affecting pollination and seed set. Control thrips by spraying 5ml/20l of ALONZE 50EC, 40ml/20l of DEFENDER 25EW, or 30ml/20l of PROFILE 440EC.
  8. Bean flies: The larvae of bean flies tunnel through the main stem and cause significant damage. In severe cases, seedlings may die, older plant leaves turn yellow and become stunted, and stems become thicker and crooked. To control bean flies, dress the seeds with 3ml/kg of SHIELD 600FS. Drench the soil with 20ml/20l of EMERALD 200SL or 60ml/20l of PROFILE 440EC. For controlling adult bean flies, spray 10ml/20l of KINGCODE ELITE 50EC, PENTAGON 50EC, or LEXUS 247SC.

Diseases

  1. Damping off: This disease leads to the rotting of seeds before emergence and seedling rot after emergence. To address damping off, drench the soil with 100g/20l of PYRAMID700WP or spray the crop with 50g/20l of CHANCETYL ELITE 800WDG.
  2. Anthracnose: Anthracnose affects various above-ground parts of the crop, with pods being particularly vulnerable. Infected pods develop brown sunken lesions covered with pink spores under humid conditions. The seeds may become brownish black. Control anthracnose by spraying 15g/20l of RANSOM 600WP, 20ml/20l of DUCASSE 250EW, or 10ml/20l of ABSOLUTE 375SC.
  3. Powdery mildew: Powdery mildew causes the formation of white powdery patches on leaves and other plant parts, gradually expanding and covering the entire surface as the infection progresses. Severely infected parts turn yellow, become distorted, and lead to defoliation. Treat powdery mildew by spraying 15g/20l of RANSON 600WP, 10ml/20l of DOMAIN 250EC, or 10ml/20l of BRADLEY 500SC.
  4. Bacterial blight: Bacterial blight causes the formation of small brown blotches on leaves, which enlarge as the infection progresses, ultimately leading to leaf drop and plant death. Control bacterial blight by spraying 50g/20l of GREENCOP 500WP, COLONIZER 440WP, or TRINITY GOLD 425WP.
  5. Rust: Rust disease manifests as reddish-brown blisters, primarily on the underside of leaves, stems, and pods. In severe cases, both sides of the leaves are covered with rust pustules, leading to defoliation, while the pods may shrivel. Spray the crop with 10ml/20l of MILESTONE 250SC, 15g/20l of RANSOM 600WP, or 20ml/20l of DUCASSE 250EW to control rust.
  6. Yellow mosaic: Yellow mosaic is a viral disease transmitted by whiteflies, resulting in significant losses. Infected leaves become necrotic, and affected plants are stunted, mature late, and produce few flowers and pods. The pods are usually reduced in size and turn yellow. Control the whitefly vectors by spraying 10g/20l of TAURUS 500SP or 30ml/20l of PROFILE 440EC.

Implementing appropriate control measures for these diseases can help manage and mitigate their impact on green gram crops.

NUTRITION

To ensure optimal production, it is important to supply the green gram crop with sufficient nutrients. This can be achieved by applying both basal and foliar fertilizers.

Here are some recommended practices:

  1. During planting, it is beneficial to apply Diammonium phosphate (DAP) fertilizer. The exact amount should be determined based on the organic matter content of the soil. Additionally, incorporating manure into the soil can also provide valuable nutrients.
  2. About 4 to 5 weeks after germination, top dressing should be carried out using Calcium ammonium nitrate (CAN) fertilizer. This helps provide additional nutrients during the growing period.

To enhance nutrient uptake, promote plant growth, and reap other benefits, it is advisable to mix a product called Humipower with the basal fertilizer or manure. The recommended ratio is 1kg of Humipower to 50kg of basal fertilizer or 1 ton of manure. Incorporating Humipower in this manner can improve nutrient absorption by the plants and stimulate growth.

By following these fertilization practices, the green gram crop can receive the necessary nutrients for optimal development and productivity.

Here are some recommended foliar feeds for green gram crops:

  1. OPTIMIZER: A dosage of 10ml/20l is suggested for this foliar feed. OPTIMIZER helps manage plant stress, enhance immunity, and supply both micro and macro nutrient elements. It also aids in preventing flower abortion and provides various other benefits. This foliar feed can be sprayed at any stage of crop development.
  2. GOLDCHANCE SERIES: To support the plant’s growth and development at different stages, a dosage of 50g/20l of GOLDCHANCE SERIES is recommended. This foliar feed contributes to increased yields by taking care of the plant’s nutritional needs throughout its growth cycle.
  3. LAVENDER: Particularly important during the early and vegetative stages of plant growth, a dosage of 20ml/20l of LAVENDER is advised. This foliar feed plays a vital role in promoting healthy growth during these crucial growth periods.

By using these recommended foliar feeds, green gram crops can benefit from enhanced nutrient uptake, stress management, improved growth and development, and ultimately, increased yields.

WEED CONTROL

Weeds pose a significant threat to the target crop as they compete for vital resources such as nutrients, water, space, and sunlight. They can also harbor pathogens, further affecting crop health. To minimize the losses caused by weed infestations, it is crucial to maintain a weed-free environment in green gram gardens.

During the flowering stage of the crop, it is advisable to minimize weeding activities to avoid unnecessary disturbances that could potentially impact pollination and yield.

Prior to planting the crop, spraying weeds with CLAMPDOWN 480SL at a dosage of 200ml/20l can effectively reduce weed growth throughout the growing season.

Please note that when conducting any foliar spray, whether it involves insecticides, fungicides, foliar feeds, or herbicides, it is recommended to mix the product with INTEGRA at a dosage of 3ml/20l. INTEGRA serves as a sticker, spreader, and penetrant, enhancing the effectiveness of the product applied to the crop.

By implementing these weed management practices, the green gram crop can thrive in a weed-free environment, ensuring better access to essential resources and reducing potential losses associated with weed infestations.

MATURITY, HARVESTING & STORAGE

Green grams typically reach maturity within a range of 60 to 90 days after sowing, with the exact timing influenced by environmental conditions and the specific variety being cultivated.

Harvesting should be conducted when a significant portion of the pods have turned black. This can be achieved by either picking individual pods or uprooting the entire plant.

Delayed harvesting can lead to pod shattering and potential losses, such as increased susceptibility to pest infestations.

After harvesting, it is important to allow the pods to dry for approximately 2 to 3 days. Following the drying period, the pods should be threshed and winnowed to remove any extraneous material, making them ready for consumption or storage.

Since green grams are highly susceptible to bruchid beetle infestations, it is crucial to store them promptly after sun drying. This can be done in airtight containers or gunny bags placed in a clean, well-ventilated room. To ensure longer storage periods, it is advisable to treat the seeds with appropriate seed treatments.

Please note the following:

  • Proper drying of green grams is essential to prevent contamination by aflatoxins and the development of pathogens.
  • Infected seeds should be separated from sound ones and not mixed together.

By following these guidelines, the quality and storability of green grams can be maintained, reducing the risk of contamination and seed damage.

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