Guide to French Beans Farming in Kenya

By Value Magazine Team on 28 January 2020 at 11:36 am
French beans in Kenya

Locally known as Mishiri, French beans have traditionally been grown in Kenya for Export. As time has gone by local consumption of french beans has been increasing. 

French beans can be grown both on a large scale and small scale. However, it is recommended to grow french beans on a small scale, with staggered planting where possible. This is due to the fact that farming french beans is labor intensive. 

French beans in Kenya is grown for both the fresh market and processing.  They can be processed by canning and freezing. 

In Kenya, the peak export market is between October and May. 

French beans take 45 to 50 days to mature, making them a good crop for farmers seeking short production cycles. 

 

French Bean Varieties. 

French beans, also known as Green Beans, Fine Beans or Snap Beans are immature pods of the common bean (Phaseolus Vulgaris). 

The varieties of french beans are:

  • Monei
  • Samantha
  • Amy
  • Teresa
  • Julia
  • Vernado
  • Bronco
  • Coby
  • Expadia
  • Bakara
  • Claudia
  • Tokai
  • Pekera
  • Super Monei
  • Morgan
  • Paulista
  • Cupvert
  • Gloria
  • Tonivert
  • Rexas

The varieties of french beans required by the market are straight, fleshy, long and rounded in cross-section. 

 

French Beans

Ecological requirements for growing french beans

  • Temperature

French beans grow well at the optimum temperature ranges of 20 to 25 degrees celsius.  They can grow in temperatures of between 14 to 32 degrees celsius, but extreme temperatures lead to poor flower development and fruit set. They mature earlier in warmer areas. 

  • Altitude

French beans grow well at an altitude between 1000 - 2100m above sea level. 

  • Rainfall

If relying on rain to grow french beans, well-distributed rainfall of 900-1200mm per annum is required

  • Soil

French beans require well-drained loam soils to heavy clay soils have high organic matter content. The optimal pH is 6.5 to 7.5 but they can tolerate a lower pH up to 4.5. 

Crop Rotation for French Beans

French beans should not be grown at most twice on the same parcel of land without other crops being grown in rotation. Crop rotation when growing french beans help control weeds, disease, soil erosion, reduces pest populations and rejuvenates the soil. 

Seed rate for french beans

The seed rate for planting french beans is 30kg per acre, planting at 1kg per 100ft row at the spacing of 3 inches. 

Make sure you use certified seeds from reputable sellers, where the seeds are disease-free and well sorted. If you are growing french beans on contract, the contracting company usually supplies seeds. 

Dress the seeds with Fernasa-D (a combination of Lindane and Thiiram) at the rate of 3 grams (2 flat teaspoons) per kilogram of seed. 

Manure Application when growing French beans

Manure at the rate of 10 tonnes per hectare should be applied during planting. This is especially where the soils have low quantities of organic matter. Apply the manure in the planting furrows and ensure it is well worked into the soil before planting.  

Fertilizer requirements for french beans

At the time of planting, 200kg of DAP fertilizer per hectare is required. Apply the fertilizer in the planting furrow and mix thoroughly with the soil before planting the seeds.

Topdressing is done with CAN fertilizer, at the rate of 100kg per hectare, when the plants are at the first three leaves stage. Top dress again, at the same rate at the onset of flowering. 

Foliar feed is applied every 2 weeks, from the fourth week after planting to the middle of the podding season. Examples of recommended foliar feeds are Bayfolan and Rapid-Grow. 

Field Established for French Beans

  • Growing Season for French Beans

Planting starts at the onset of rains. With irrigation, French beans can be grown all year round but the main export season is from October to May. Sowing should be scheduled such that most of the crop is ready between October to mid-December, and from mid-January to the end of May.

  • Planting Schedule for French Beans

To maintain continuous production, planting should be staggered at 2-3 weeks intervals in conveniently sized plots.

  • Spacing for French Beans

Beans should be sown in single rows of 30 by 15cm, (1 seed per hole); or double rows 60 by 30 by 10cm. It is advisable to plant in blocks of four single rows, separated by a path of about 50cm, for ease of management.

  • Seed Rate for French Beans

One hectare takes a total of 50-60 kg of bean seed.

French beans are sown directly into a well-prepared seedbed.

  • Picking time for French Beans

In warm areas, beans take 45 to 50 days from planting to first picking.

Irrigation for french beans

Regular water supply is essential as moisture affects yields, uniformity, and quality.  It is advisable to grow the beans on ridges and use furrow irrigation in heavy clays. This is because beans are very sensitive to waterlogging.

To maintain a continuous production especially during the off-season, irrigation is essential.

It is recommended to apply 35 mm/week at planting to 10 days post-emergence and 50mm/week thereafter to the flowering stage. Water could be applied through furrow or overhead irrigation.

Mulching for french beans

Mulching helps establishment under wet conditions because young bean seedlings are prone to a fungal infection caused by soil splash

Weed control for french beans

Timely and thorough weeding is absolutely essential.  The first weeding should be done 2-3 weeks after emergence. The second weeding should follow 2-3 weeks later. Care should be taken to avoid damaging the shallow roots, especially during the first weeding. Crops should not be weeded at flowering time and when the field is wet to avoid flower shedding, the spread of diseases and soil compaction. The use of herbicides could be economical for the commercial French beans grower.  The following pre-emergence herbicides can be used: -.

  • Lasso 4 EC (Alachlor) at 3 Litres in 400 litres of water per hectare
  • Stomp (Pendimethalin) at 2.5 Litres in 400 litres of water per hectare
  • Basagran (Bentazon) can be applied post-emergent at 2.5-3lts/ Ha for control of broad-leaved weeds.

Diseases affecting French Beans

Rust

Rust in french beans disease is caused by the fungus Uromyces appendiculatus. This is a very serious disease to French Beans and other food beans.  The Development of the disease is favoured by high humidity conditions.

The disease is recognized by the presence of slightly raised, small white spots on the surface of the lower leaf. The spots turn red to dark brown after a few days.

Controlling rust on french beans is done by:-

  • Crop rotation
  • Use of tolerant varieties.
  • Chemical sprays such as: Baycor 30% EC , Bitertanol, Anvil, Alto 100  SL, or Dithane M45 should be applied after every two weeks.

Angular Leaf Spot

Angular leaf spot is a fungal disease caused by Phaeoisariopsis griseola. The Leaves, stalks, and pods have angular brown or red coloured spots with purple edges and grey to brown centres. The leaves may then fall prematurely.

Angular leaf spot can be controlled by 

  • By use of healthy, certified seeds.
  • Treat Seeds using chemicals such as  fernasan-D, at 3gm per kg of seed.
  • Spray with chemicals such as benomyl (or benlate)

Root Rots

Root knots are fungal diseases caused by the fungus Rhizoctonia spp, Pythium spp Sclerotium spp etc.

Affected plants show yellowing and drying of stem at soil level. Stunting may also occur.  The crop may also show poor seedling establishment, uneven growth, chlorosis and premature defoliation of severely infected plants.

Root Rots can be controlled by: 

  • Seed dressing with a chemical such as: Fernasan-D , at 3gm per kg of seed, or Quitozene.
  • Drenching with chemicals such as: Brassicol (or Quitozene), Benomyl (or Benlate), or Bavistin, during the vegetative stage.

Bacterial Blights

Bacterial Blight is caused by Pseudomonas Phaseolicola and Xanthomona phaseoli . It is a serious disease for beans in Kenya, especially in cool and wet areas. The disease is spread through splashing from exuding lesions and plant debris.

Plants show ring-like spots on the leaves, drying of leaf margins, yellowing and water-soaked pods.

Bacterial Blights can be controlled by 

  • Use of certified seeds.
  • Roguing and destruction of affected plants.
  • Crop rotation.
  • Chemical sprays using copper based fungicide such as: kocide 101.

Anthracnose

The disease is caused by a fungus known as Colletotrichum lindemuthianum. The fungus is seed-borne and affects all aerial plant parts.  It is spread by rain splash, wind or mechanical contact. The disease usually occurs in cool, damp weather.

Anthracnose is characterised by the appearance of sunken, brown spots with black edges on pods; angular brown spots on leaves; and oblong stripes on stems.

Anthracnose can be controlled by:

  • Use of certified seeds.
  • Field sanitation.
  • Crop rotation.
  • Use of resistant varieties.
  • Foliar sprays using chemicals such as: Benomyl, Mancozeb, propineb.

 

Bean Common Mosaic Virus (BCMV)

The disease is seed-borne and it is transmitted by aphids.

The symptoms of Bean Common Mosaic Virus disease vary with variety, stage of growth, and environmental factors. They include a mosaic (i.e. mottling, Curling and stunting of leaves,) systemic Necrosis and local malformations.  The leaves may roll, malformed and general stunting of the pant. The plant produces an excessive number of Lateral shoots.

Bean Common Mosaic Virus is controlled by 

  • Use of certified seeds.
  • Plant resistant varieties
  • Rouging of infected plants.
  • Control of aphid vectors using insecticides.

Powdery mildew

It is caused by a fungus known as Erysiphe spp.

Powdery mildew attacks stem, leaves, flowers, and pods which appear covered with white powdery growth which turns black latter. In severe cases, the leaves turn yellow and drop off.

Powdery mildew can be controlled by:-

  • Field hygiene
  • Crop rotation
  • Chemical fungicides eg. Dithane M45, Antracol, Bayleton

Downy mildew

Downy mildew is caused by a fungus known as peronospora spp. The underside of leaves exhibits white to greyish growth which later covers the whole leaf surface.

Downy mildew can be controlled by: 

  • Field hygiene
  • Crop rotation
  • Chemical fungicides eg. Dithane M45, Antracol, Bayleton

Pests affecting French Beans

Root Knot Nematodes

Root knot is probably the most common nematode and causes the most damage.

Root Knots attack roots causing lesions, root galls or swellings, plant stunting and wilting of severely infected plants.  The lesions also serve as entry points for bacteria and fungi. Affected plants are dwarfed and have distorted leaves.

Control of root knots can be done by:- 

  • Crop rotation with non-susceptible crops such as maize and grasses.
  • Good weed control to remove weeds which are also hosts to the Nematodes.
  • Leaving fallow infested fields during dry weather.
  • Soil application of 5 gm/m² Mocap at planting, or 6-10 gm/m2 Ethoprophos, 2-3 times a year.

Bean Fly

The adult of the Bean Fly is a small 2 winged insects which can be seen resting on leaves where it lays the eggs.  The damage is caused by the larvae which mine the stem. The larvae also feed on the cotyledons of seedlings before or after emergence.    Affected plants are yellow, stunted, and stems are cracked at the soil level

The bean fly can be controlled by spraying with chemicals such as:

  • Cypermethrine at 100ml/20lt at 7 days intervals,
  • Fenvalerate at 100ml/20lts at 7 days interval.
  • Karate and decis could be applied in the stages that follow through the harvesting period, at weekly intervals.

Soils should be treated with chemicals such as:

  • Triazopho, at 30-60 ml/100lt, at 10-14 days intervals, or Chlopyrifos at 150ml/100lts. At 7 days intervals. For Triazophos and chlopyrifos, allow 21 and 7 days pre-harvest interval respectively.

Seeds should be treated with chemicals such as: –

  • Imidacloprid at 570gm/100kg of seeds.
  • Cypermethrin at 100 ml/20L At 2 weeks intervals
  • Fenvalerate at 100ml/20lts at 7 days intervals.

Bean Thrips

Bean thrip nymphs and adults cause a lot of damage by feeding and puncturing flower structures.

They can be controlled by:-

  • Foliar spray before crop flowering
  • Apply Karate Decis or Ambush CY during flowering

Aphids

Aphids cluster on plant stems, leaves, and bean pods. They suck plant sap and cause the plants to stunt. They can be controlled by using chemical sprays as for bean fly above.

Red Spider Mites

Red spider mites are tiny organisms. They damage the leaves which turn silvery and brownish in colour. Infested leaves have cobwebs on the lower leaf surface.

Red spider mites can be controlled by:-

  • Weed control to remove alternate hosts.
  • In severe infestation, burn the bean straw.
  • Spray with chemicals such as Kelthane (or Dicofol), Cabaryl, Dimethoate, Tedion (or Tetradifon 18% E.C). The safety period for Kalthane is 7 days, while. for the others it is 14 Days.

Cutworms, Beetles and Caterpillars

These pests are active at night and hide during the day. They cut stems of young plants above or below soil level. They also feed on plant foliage.

They can be controlled by treating the soil with chemicals such as Chlorpyrifos,, at 150150ml/100lts, at 7 days intervals. Observe 7 days pre-harvesting interval.

They can also be controlled by using foliar spray chemicals such as: –

  • Deltamethrin, at 30-50 ml/20lts, at 7-10 days interval and 7 days pre-harvest interval.
  • Cabarl, at 50gm /20lts, at 15 to 21 days intervals and 14 days pre-harvest Interval..
  • Malathion at 30-35ml/20lts and 14 days pre-harvest interval.
  • Fenitrothion at 40 ml/20lts. (14 days intervals, 7 days pre-harvest interval).

American ballworm

The American Ballworm larvae bores holes in flower buds and young maturing pods. Pods either fails to form or don’t develop to maturity.

They can be controlled by:-

  • Foliar sprays with Bestox, Thuricide, Desis.
  • Physical removal.
  • Weed control.

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Author

By Value Magazine Team

Value Magazine was founded in 2018 by James Mutuku, a farmer with interests in poultry, horticulture and fruit farming. The goal of Value Magazine is to offer beneficial content on agribusiness, value addition, manufacturing, and productivity.  We believe not only in producing but also adding value to the product. 

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