French beans, scientifically known as Phaseolus vulgaris, are members of the Fabaceae family and are specifically bred and cultivated for their pods and seeds. Despite having relatively low consumption rates within the country, they hold a prominent position as one of the leading crops in the export market.
Within Kenya, French beans are primarily cultivated in warm-wet regions such as Nakuru, certain areas of Kajiado, Thika, Murang’a, Machakos, Uasin Gishu, Western Kenya, Kisumu, Kirinyaga, Nyeri, and Naivasha.
By utilizing irrigation techniques, it becomes possible to grow French beans throughout the entire year.
Health benefits and nutritional value of French beans
- French beans are an excellent natural support for weight loss due to their low sodium, saturated fat, and cholesterol content.
- They are abundant in folates, which play a crucial role in preventing neural tube defects in the fetus, especially when consumed during pregnancy.
- French beans are a valuable source of various essential nutrients such as phosphorous, calcium, copper, potassium, magnesium, protein, fat, starch, and omega-3 fatty acids, all of which contribute to overall body health.
- They are also a rich source of vitamins A, B, D, and K, providing important nutritional benefits.
- Being high in dietary fiber, French beans aid in the regulation of body fat and help maintain a healthy weight.
- Additionally, they contain flavonoids and antioxidants that counteract the harmful effects of free radicals in the body, thereby preventing premature aging.
Soil conditions: French beans thrive in well-drained soils that are enriched with organic matter. The ideal soil pH for their growth ranges from slightly acidic to alkaline, specifically around 6.5-7.5.
Temperature requirements: The optimal temperature for growing French beans falls within the range of 20-25°C. However, different varieties of French beans can tolerate temperatures ranging from 14-32°C. It’s worth noting that extremely high temperatures can negatively impact flower development and pod formation.
Altitude considerations: French beans perform best within an altitude range of 1000-2100 meters above sea level (asl). However, in warmer regions, they tend to mature more rapidly.
Rainfall patterns: For rain-fed farming, French beans require well-distributed annual rainfall ranging from 900-1200mm. In cases of inadequate rainfall, irrigation becomes necessary. Excessive rainfall or prolonged dry spells are unfavorable and can lead to lower yields. Moreover, excessive rainfall during the flowering stage can result in flower abortion and an increased incidence of diseases.
French beans come in various color variations, including green, yellow, and purple, among others.
In Kenya, numerous varieties of French beans are cultivated, including Samantha, Boston, Serengeti, Amy, Belcampo, Julia, Paulista, Rexas, Lomami, Hawaii, Morgan, Pekera, Picasso, Buffalo, Tokai, Teresa, Gloria, Cupvert, Seagull, Espadia, and many more.
To cultivate French beans on an acre of land, approximately 25-30kg of certified seeds are needed, with the specific quantity depending on the chosen variety.
The spacing requirements for planting French beans may vary depending on factors such as the variety, water availability, and soil fertility. However, for single rows, it is recommended to space the seeds at a distance of 30x15cm (with one seed per hole). Alternatively, for double rows, a spacing of 60x30cm is advised.
To facilitate convenient crop management, it is advisable to plant French beans in blocks consisting of four single rows. These rows should be separated by a 50cm pathway.
LAND PREPARATION & PLANTING
French beans are propagated through direct sowing of seeds into the field.
To ensure proper growth, it is recommended to prepare the land well in advance, allowing sufficient time for weeds to dry up and decompose before the actual planting takes place.
- Begin by applying CATAPULT® 480SL at a rate of 200ml per 20L of water to effectively control both broadleaf and grass weeds.
- Plough the land and ensure it is leveled with a fine tilth, providing a suitable seedbed for planting.
- Prepare a mixture of soil, manure, and DAP (Di-Ammonium Phosphate). To enhance nutrient uptake and stabilize soil pH, combine 1kg of HUMIPOWER® with 50kg of DAP and/or 1 ton of manure.
- Plant the French bean seeds, spacing them either at 60x20cm (with two seeds per hill) or 30x15cm (with one seed per hill). Place the seeds at a depth of 1-2 inches.
- Cover the seeds with loose soil, ensuring they are adequately protected and positioned for optimal growth.
- It is recommended to use certified seeds obtained from trustworthy seed suppliers to ensure quality and reliable results.
- For rain-fed production, it is advisable to commence planting at the beginning of the rainy season to optimize water availability for the crops.
- Soaking the seeds in OPTIMIZER® at a rate of 20ml per 1L of water overnight before planting can promote more uniform and faster germination.
- Typically, germination of French bean seeds takes place within a timeframe of 7 to 14 days, allowing for the emergence of healthy seedlings.
The presence of sufficient moisture greatly influences the consistency, productivity, and overall quality of crops. Hence, in situations where rainfall is insufficient, providing water through irrigation becomes crucial. Additionally, when cultivating French beans in heavy clay soil, it is recommended to adopt ridge planting and furrow irrigation methods due to the crop’s high susceptibility to water logging. Insufficient water supply during the flowering and pod formation stages can result in the abortion of flowers and the development of curved pods, ultimately leading to reduced yields.
The presence of weeds in a crop can have a detrimental impact on its productivity, as they compete with the crop for essential growth factors and can also act as hosts for diseases and pests. Hence, it is vital to implement effective weed management practices. One recommended approach is to use HOTLINE® 450SC, a selective herbicide that controls both broadleaf and grass weeds, as a pre-emergent treatment. The recommended application rate is 50ml per 20 liters of water. However, during the flowering stage, it is advised to refrain from weeding to avoid disturbing the crop, which could lead to the shedding of flowers.
To provide support for climbing French bean varieties, which typically reach a height of approximately 6 feet, trellises or poles can be utilized.
This practice is recommended for crops that are not part of the Fabaceae family. It assists in controlling weeds, managing pests and diseases, reducing soil erosion, and revitalizing organic matter in the soil.
In order to attain maximum crop yields, it is crucial to apply basal and foliar fertilizers in a timely manner. Additionally, the addition of manure is particularly important for soils that have limited or no organic matter.
Before planting, it is recommended to apply 100Kg of DAP per acre by thoroughly incorporating it into the soil. DAP is preferred due to its higher phosphorus content, which greatly aids in root development for the crop. Alternatively, other phosphatic fertilizers like TSP can be utilized.
Around one week after germination, the young plants should be sprayed with either 20ml of LAVENDER SUPER STARTER® diluted in 20 liters of water or 50g of GOLDCHANCE SUPER START® diluted in 20 liters of water. These products promote early establishment of the crop, along with providing other benefits.
At the initial stage of the crop’s development, it is recommended to apply 50kg of CAN (Calcium Ammonium Nitrate) per acre when the crop reaches the three-leaf stage. Similarly, when the crop enters the flowering stage, another 50kg of CAN per acre should be applied. CAN is beneficial as it aids in nitrogen fixation in the soil, leading to greener leaves that are responsible for synthesizing food for the plant. Alternatively, other nitrogenous fertilizers like urea can be used as well.
For foliar application, the crop can be sprayed with either 50g of GOLDCHANCE SUPER GROWTH® or 20ml of LAVENDER SUPER GROWTH & VEGETATIVE® diluted in 20 liters of water. These products provide essential nitrogen along with other vital nutrients.
When the crop begins flowering and starts setting pods, it is advisable to spray it with either 50g of GOLDCHANCE SUPER FLOWERS & FRUITS®, 20ml of DIMIPHITE®, 50g of GOLDCHANCE MULTISUPER K®, or 20ml of LAVENDER SUPER FLOWERS & FRUITS® diluted in 20 liters of water. These products are rich in nutrient elements that promote the production of high-quality pods. Additionally, applying 30ml of VITABOR GOLD® per 20 liters of water can help prevent flower abortion.
- Conducting soil analysis is crucial as it enables the assessment of soil fertility levels.
- It is recommended to mix all basal fertilizers with HUMIPOWER® at a ratio of 1kg of HUMIPOWER® per 50Kg of fertilizer.
- OPTIMIZER® is an organic biostimulant that plays a vital role in promoting plant growth and managing stress. It can be applied at any stage of the crop’s growth and development.
- Excessive use of nitrogenous fertilizers should be avoided as it can result in excessive vegetative growth, potentially compromising pod formation.
MAJOR PESTS & DISEASES
Bean fly infestation occurs when the larvae burrow into the stems of the plants, causing damage to the vascular tissue. This results in reduced plant vigor and drooping petioles in older crops. In severe cases, the infestation can even lead to the death of seedlings. The period of greatest risk for infestation is typically 3-4 weeks after emergence. Affected plants exhibit yellowing, stunted growth, and stem cracking at the soil level.
To address the issue, it is recommended to spray the affected crops with either 10ml of EMERALD® 200SL, 5g of PRESENTO® 200SP, or 10ml of KINGCODE ELITE® 50EC per 20 liters of water.
Thrips cause damage by feeding on leaves and flower structures through puncturing. Both nymphs and adult thrips contribute to this damage. In cases of severe infestation, flower and flower bud abortion can occur, and leaves may also fall off.
To mitigate the issue, it is advisable to spray the affected plants with either 5ml of ALONZE® 50EC, 40ml of DEFENDER® 25EC, or 5g of PRESENTO® 200SP per 20 liters of water.
Aphids are small insects with soft bodies, appearing in green, black, or brown colors. They tend to cluster on stems, leaves, and pods, where they extract plant sap through sucking. This feeding behavior results in stunted growth and deformities in the affected plant parts. Additionally, aphids produce honeydew as they feed, which promotes the growth of sooty mold. The presence of sooty mold reduces the photosynthetic area of the plant.
To address aphid infestations, it is recommended to spray the affected plants with either 10ml of PENTAGON® 50EC, 5g of PRESENTO® 200SP, or 10ml of KINGCODE ELITE® 50EC per 20 liters of water.
To eliminate sooty mold, spraying the plants with 100ml of JAMBO CLEAN® diluted in 20 liters of water is advised.
Red spider mites are small pests with a reddish-yellow coloration that are typically found on the undersides of leaves. Their feeding habits result in the formation of yellow specks on the leaf surfaces. In cases of severe infestation, webs can be observed on the undersides of the leaves.
To address red spider mite infestations, it is recommended to spray the affected plants with either 5ml of ALONZE® 50EC, 10ml of BAZOOKA® 18EC, or 40ml of DEFENDER® 25EC per 20 liters of water.
Whiteflies are insects with a white appearance that extract plant sap through feeding, leading to curled and distorted leaves. Eventually, the affected leaves may drop off. Whiteflies also secrete honeydew during feeding, which promotes the growth of sooty mold on the leaves, negatively impacting photosynthesis.
To address whitefly infestations, it is recommended to spray the affected plants with either 10g of TAURUS® 500SP, 5g of PRESENTO® 200SP, or 10ml of EMERALD® 200SL per 20 liters of water.
To remove the sooty mold, spraying the plants with 100ml of JAMBO CLEAN® diluted in 20 liters of water is advised.
The African bollworm is a pest that causes damage by tunneling holes into pods. It feeds by inserting its head inside the pod while leaving the rest of its body outside, resulting in a reduction in the quality of the affected pods. Additionally, the African bollworm feeds on leaves and flowers.
To address infestations of the African bollworm, it is recommended to spray the affected plants with either 10ml of KINGCODE ELITE® 50EC, 10ml of PENTAGON® 50EC, or 5g of PRESENTO® 200SP per 20 liters of water.
Cutworms are caterpillars that typically have a brown to black coloration and are commonly found in the soil. They cause damage by cutting the stems of young plants either below or above the soil level. Cutworms are nocturnal pests, being active at night and hiding during the day.
To address cutworm infestations, it is recommended to drench the soil with either 20ml of PENTAGON® 50EC or 10g of LOYALTY® 700WP per 20 liters of water.
Rust is a fungal infection that manifests as slightly raised reddish-brown pustules on leaves, pods, and stems. Severe infections have the potential to cause the death of the entire crop.
To address rust infections, it is recommended to spray the affected plants with either 10ml of MILESTONE® 250SC, 20ml of DUCASSE® 250EW, or 10ml of DOMAIN® 250EC per 20 liters of water.
Downy mildew is a disease that initially develops on the underside of the leaf, resulting in the formation of whitish or grey fungal growth. Simultaneously, the upper side of the leaf undergoes yellowing, and the pods exhibit whitish patches.
To combat downy mildew, it is recommended to spray the affected plants with either 50g of TOWER® 720WP, 10ml of MILESTONE® 250SC, or 40ml of KATERINA® 720SC per 20 liters of water.
Anthracnose is a disease that causes the formation of sunken lesions on pods and stems, ranging in color from brown to black. Additionally, the leaves develop black spots, which can disrupt the rate of photosynthesis.
To address anthracnose infections, it is recommended to spray the affected plants with either 20ml of DUCASSE® 250EW, 10ml of DOMAIN® 250EC, or 15ml of JUPITER® 125SC per 20 liters of water.
Bacterial blight is a disease characterized by the initial appearance of small brown blotches on the leaves. These blotches gradually increase in size as the infection progresses, ultimately resulting in leaf fall and the eventual death of the plant.
To address bacterial blight, it is recommended to spray the affected plants with 50g of GREENCOP® 500WP per 20 liters of water. GREENCOP® 500WP is a copper-based product that helps suppress the activity of the pathogen causing the disease.
Fusarium wilt is a disease that leads to the sudden yellowing of leaves in infected crops, followed by their eventual defoliation. The vascular tissues of the plant also become discolored, ultimately resulting in the death of the plant.
To address Fusarium wilt, it is recommended to drench the soil with 100g of GREENCOP® 500WP per 20 liters of water. Additionally, spraying the affected plants with 50g of PYRAMID® 700WP per 20 liters of water is advised.
Damping off is a disease caused by soil-borne pathogens that result in the failure of infected seeds to germinate. Additionally, seedlings affected by damping off experience rotting and eventually die. A characteristic white cottony growth can be observed on the roots of infected young plants.
To address damping off, it is recommended to drench the soil with 100g of PYRAMID® 700WP per 20 liters of water. Additionally, spraying the affected plants with 10ml of DOMAIN® 250EC per 20 liters of water is advised.
Angular leaf spots disease manifests as the development of angular brownish spots with purple edges and grey to brown centers on affected leaves, stalks, and pods. Initially, these spots appear water-soaked. In severe cases of infection, premature leaf fall can occur.
To address angular leaf spots, it is recommended to spray the affected plants with either 10ml of DOMAIN® 250EC, 20ml of DUCASSE® 250EW, 20ml of CHARIOT® 500SC, or 10ml of MILESTONE® 250SC per 20 liters of water.
Powdery mildew is a disease characterized by the presence of a white powdery growth caused by the pathogen. As the infection progresses, the powdery growth turns black. This growth can be observed on the stems, leaves, flowers, and pods. In severe cases, affected leaves become chlorotic (yellowish) and eventually drop off.
To address powdery mildew, it is recommended to spray the affected plants with either 10ml of DOMAIN® 250EC, 20ml of CHARIOT® 500SC, or 15ml of JUPITER® 125SC per 20 liters of water.
Bean Common Mosaic (BCM) is a viral disease primarily transmitted by aphids. Infection with BCM leads to the formation of mosaic patterns on leaves, as well as leaf curling and rolling. The overall growth of the crop is stunted as a result.
To control the aphid vectors responsible for transmitting BCM, it is recommended to spray the affected plants with either 10ml of PENTAGON® 50EC, 5g of PRESENTO® 200SP, or 10ml of KINGCODE ELITE® 50EC per 20 liters of water.
- When conducting foliar sprays, it is recommended to include INTEGRA at a rate of 3ml per 20 liters of water. INTEGRA is a product that functions as a sticker, spreader, and penetrant, enhancing the effectiveness of the chemical being applied.
- For preventive measures against diseases like downy mildew, anthracnose, and leaf spots, CADILAC® 800WP can be utilized. It should be applied at a rate of 50g per 20 liters of water. CADILAC® 800WP is a fungicide specifically designed to protect plants against these fungal diseases.
HARVESTING & POST-HARVEST PROCESSES
The onset of the harvesting period typically occurs between 6 to 8 weeks after planting, varying depending on the specific variety and prevailing ecological conditions.
For optimal results, it is advisable to carry out the harvesting process in the morning. However, it should be avoided when the crop is excessively wet. Harvesting is achieved by carefully picking the pods from the plant along with their stalks, rather than pulling forcefully. This activity should be performed at regular intervals, considering market specifications. For example, fine French beans may require harvesting twice a week, while extra fine beans may require harvesting three times a week. This harvesting schedule can be sustained for approximately one month.
Harvesting the beans while they are still young promotes higher production and ensures the beans retain their delicious taste.
French beans have the potential to yield approximately 4 to 6 tonnes per acre.
It is important to take precautions to preserve the quality of the produce. For example, harvested beans should not be exposed to direct sunlight, and it is advisable to avoid overfilling the harvest boxes.
Sorting and Grading
Sorting is performed to remove broken, twisted, and perforated pods, as well as any plant debris. On the other hand, grading is carried out based on the size of the produce.
The packing process involves preparing boxes of produce that must meet the quality standard set by the European Union for French beans (standard EC 912/2001). Additionally, each box intended for the export market should prominently display specific product characteristics such as the name of the producer/exporter, size, category, origin, and other relevant details.
Immediately after packing, it is recommended to store the produce in a cold room. French beans can be stored at a temperature of around 4°C (39°F) with a relative humidity of approximately 80%. Under these conditions, French beans can maintain their quality for up to one week.
The primary market for French beans is the European Union (EU), and the export market in Kenya can be divided into two main seasons. The high demand season spans from September to March, during which the major supply comes from irrigation. In contrast, the low demand season occurs from June to September, coinciding with the long rainy season when the supply is abundant, resulting in lower prices.