FRENCH BEANS PRODUCTION

FRENCH BEANS (Phaseolus vulgaris)

French beans are immature green pods which are referred to as snap or green beans. The beans are a major export crop in Kenya whose local consumption is gradually increasing. The crop is grown by both large and smallholder farmers.
The pods vary in colour, depending on cultivar. The growth habit is both dwarf and climbing type.
The beans are grown for both fresh consumption and processing (mainly canning and freezing). French beans containing protein, fat, calcium, iron, phosphorus, vitamins A, B, D and starch.

Marketing
A major outlet for these French beans is the European Union market. The export market in Kenya falls into two major seasons:
The low demand season runs mostly from June to September every year. It is characterized by lots of supply from those who produce with the long rains and low demand from the EU market as they can produce their own by then.
The high demand season usually runs from September to around March. During this period, EU markets are faced with winter and their only option is to import and that is when Kenyan farmers benefit from production.

Ecological requirements
Altitude
The most suitable areas for the production of French beans fall within the lower Midland to Lower Highland zones at altitudes between 1500-2100m above sea level.
Rainfall
Rain fed cultivation is possible in areas with well distributed, medium to high annual rainfall of 900-1,200mm per annum, however to maintain continuous supply especially during the off-season, irrigation is essential. Up to 50mm of water per week is required.
Soils 

French beans can grow in a wide range of soil types, ranging from sandy, and loam to clay. They however grow best on friable (easily crumbled), silty loam to heavy clay soils which are well drained high in organic matter. The optimum soil pH is 6.5 to 7.5, but beans can tolerate a low pH of up to 4.5. 

Below pH 4.5, plant growth is impaired through limitation of development of the Rhizobium bacteria that are responsible for the nitrogen fixation in the galls formed on the bean roots. It’s advisable to carry out a soil test before planting. 

Temperature
French beans can grow in temperatures range for production is 14-320 C depending on the variety. The optimum temperature for production is 20-250 C. Extreme temperatures result in poor flower development and poor pod set. Seedlings will not tolerate temperature lower than 100C.
Varieties grown in Kenya
There are various varieties grown mainly for the export market. Production is determined by market preference. The varieties includes: Amy, Teresa, Samantha, Julia, Paulista, Vernando, Serengeti, Cupvert, Tokai and Bakara, Monel, Gloria, Claudia, Morgan, Amy coby, espada, Maasai and Nerina.

• Varieties for fresh market: Amy, Pekara, Teresa, Paulista, Rexas, Samantha and Cupvert.

• Varieties for Processing: Julia, Vernandon and Sasa.

Planning production
To venture into French beans production, it is important to get a reliable market first and then produce as required by the market outlet.
French beans production can be labour intensive especially during harvesting thus it require adequate provision for labour.
Pest and diseases can be a problem in production hence provisions for crop protection chemical should be made in advance

Planting season
Planting should be scheduled so that most of the crop is ready between October to mid December and from mid-January to end of May. From mid December to mid January the demand is low because of the holidays.
In warm areas, beans take 55-60 days from planting to first picking, hence, plant from mid­-August to mid-October, then plant again early in December.  

Land preparation
French beans are sown directly into the seed bed. The land should be ploughed and harrowed properly just before planting
Planting
With irrigation, French beans can be grown all year round but the main export season is from October to May.
Spacing
Single rows 30 x 15 (1 seed per hole) or double rows 60 x 30 cm may be used. The spacing will depend on the variety, soil fertility, water availability as well as climate. It is advisable to plant in blocks of about 4 rows separated by a path of about 50 cm. The seed rate required is, 25-60kg/ha (10-24kg/acre) of certified seeds depending on the variety.
Fertilizer and manure application

• Apply 200 kg/ha (80kg/acre) DAP along the rows before planting. Contact between fertilizer and seed should be avoided by mixing the fertilizer thoroughly with the soil in the planting furrow.Apply 150-kg/ha (60kg/acre) Calcium ammonium nitrate (CAN), as a top dressing in a split application. First split is applied when 2-3 leaves appear and the second at the beginning of flowering. 

• Excessive nitrogen should be avoided as it may promote vigorous vegetative growth at the expense of pod production.

• Foliar feeds are recommended to boost crop development and production. The choice of the fertilizer depends on the fertility of the soil and variety requirements.

• Use of farmyard manure is also recommended especially where soils are low in organic matter e.g. on the heavy clay and sandy soils. It should be applied in planting furrow and worked into soil before planting at the rate of 10 tons/ha

Note1 kg of seed requires 4-8 kg of fertilizer depending on the variety and soil conditions.

Crop rotation
This practice is recommended to avoid pest and disease build up. Rotation is mainly done with cassava, maize, sorghum or any other non leguminaceae family member crop. 

Weed control

• Timely and thorough weeding is absolutely essential. The first weeding should be done 2-3 weeks after emergence followed by a second weeding 2-3 weeks later.Care should be taken to avoid damaging the shallow roots especially during the first weeding.

• The crop should not be weeded at flowering time and when the field is wet to avoid flower shedding, spread of diseases and soil compaction. Use of herbicides may be economically feasible for the commercial French beans grower. Pre-emergence herbicides such as: Lasso 4 EC( Alachlor) and Stomp (Pendimethalin) can be used

• Basagran (Bentazon)-Can be applied post emergence for control of broad leaved weeds

Irrigation

• Constant supply of water is very essential because soil moisture affects yield, uniformity and quality of French beans.

• Water stress during flowering and podding causes flower abortion and curved pods leading to reduced yields.

• French beans are also very sensitive to waterlogged conditions. Therefore, where the soils are not well drained such as the black cotton soils, it is advisable to grow them on ridges. In such soils, furrow irrigation with the beans planted on the ridges is a better practice than the common system of basin irrigation. Either furrow or an overhead system of irrigation may be used.

The irrigation regime below is based on crop water requirement at various stages of growth as well as the soil and weather conditions. The recommendation is as follows:
1. Planting to 10 days (Post emergence) apply 35 mm per week
2. 10 days Post emergence to flowering blooms apply 50 mm per week
3. At Podding stage apply 35 mm per week.

Supporting French beans
The climbing variety which grows to about 1.8m (6ft) high needs to be supported. This variety requires trellises, poles, or other means of support at least 200cm (8ft) high.

Pests

Root Knot Nematodes
These 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

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 nematicides

Bean Fly (Ophiomyia spp, Phorbia spp)

The adult is a small 2 winged insect 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

Control
Spray with recommended insecticide

Bean Thrips (Megalothrips Spp)
The damage is caused by the nymphs  and adults which feed and puncture flower structures. 

Control

Foliar spray before crop flowering with recommended insecticides

Aphids (Aphids fabae)
Aphids cluster on plant stems, leaves, and bean pods. They suck plant sap and cause the plants to stunt.. Control-As for bean fly above.

Red Spider Mites (Tetranychus Telarius)
These are tiny organisms also known as red     spider mites, since they are in the same group as spiders.  Their main damage is on the leaves    which turn silvery and brownish in colour. Infested leaves have cobwebs on the lower leaf surface.
Control

Weed control to remove alternate hosts.

In severe infestation, burn the bean straw.

Spray with miticide

Cutworms, Beetles and Caterpillars

These 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.

Control.
Treat soil with recommended chemicals

American ballworm (Heliothus armigera)

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

Control

• Foliar sprays with recommended insecticides

• Physical removal

Diseases

Rust
The 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.

Control

• Crop rotation

• Use of tolerant varieties.

• Chemical recommended fungicides

Angular Leaf Spot
This is a fungal disease caused by Phaeoisariopsis griseola.
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.

Control

• By use of healthy, certified seeds.

• Treat Seeds using recommended fungicides

• Recommended fungicides

Root Rots
These are fungal diseases caused by the fungus Rhizoctonia spp, Pythium spp Sclerotium spp
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.
Control

• Seed dressing with a recommended fungicide

• Drenching with recommended fungicide during the vegetative stage.

Bacterial Blights
The condition 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.
Control

• Use of certified seeds.

•  Rouging and destruction of affected plants.

• Crop rotation.

• Chemical sprays using copper based fungicide

Anthracnose
The disease is caused by a fungus known as Colletotrichum lindemuthiamum. 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.
The disease is characterised by appearance of sunken, brown spots with black edges on pods; angular brown sports on leaves; and oblong stripes on stems.

Control

• Use of certified seeds.

• Field sanitation.

• Crop rotation.

• Use of resistant varieties.

• Recommended fungicides 

Bean common Mosaic Virus (BCMV)
The disease is seed-borne and it is transmitted by aphids.
The symptoms of this disease vary with variety, stage of growth, and environmental factors.
They includes a mosaic (i.e. mottling, Curling and stunting of leaves,) systemic Necrosis and local malformations.  The leaves may roll, malform and general stunting of the pant.  The plant produces excessive number of Lateral shoots.
Control

• 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. Attacks stems, leaves, flowers, and pods which appear covered with white powdery growth which turn black latter. In severe cases the leaves turn yellow and drop off.

Control

• Field hygiene

• Crop rotation

• Recommended fungicides

Downy mildew
Caused by a fungus known as perenospora spp. The underside of leaves exhibit white to greyish growth which later cover whole leaf surface.
Control

• Field hygiene

• Crop rotation

• Use Chemical fungicides

Harvesting

• Picking of pods begins 6-8 weeks after planting, depending on the area and variety, and continues for about 1-2 months.

• Clean harvesting equipment should be used and workers should maintain personal hygiene.

•  The pods are carefully picked and not pulled from the plants and should have the stalk attached to them.

•  Picking should be at regular intervals, as per buyer specifications. Harvesting may be done twice a week for the fine beans and three times a week for the extra fine beans. This continues for around three weeks. 

• Harvesting under rain or wet conditions is not recommended. If this cannot be avoided, the produce should be placed on a clean cloth, under shade, to dry before packing. If the pods are soiled, they should be immersed in clean water and placed on a clean dry cloth to dry.

Yields

• Yields of 9 to 15 tons/ha are attainable. An acre of land should give you 6 tons of French beans within 2 ½ months.

• 1kg of seeds may produce 200-600 kg of produce depending on the variety and crop management.

Post-harvest handling

•  The harvested pods should be carefully placed in clean plastic containers and protected from direct sun.

• The containers should be covered with moist clean cloths (preferably white cotton) to maintain low temperatures.

•  In cases of soiled pods, clean by immersing them in clean water and handle gently to avoid bruises.

• The pods should be taken to the grading shed (or put under shade) and sorted out to remove broken, malformed, overgrown, off-types and insect damaged pods.

Grading

• French beans intended for marketing should meet the following minimum quality requirements:

• Beans should be intact, sound, of fresh appearance, clean and free from excess external moisture

• Beans should be of specified size and of such a state as to enable produce to with stand transport and handling so as to meet market requirements at the destination.

•  Extra fine pods should be very tender, turgid, seedless, with no strings, and free from any defects. The width of the pods (maximum diameter) should be less than 6 mm and the minimum length of 10cm.

• The fine pods may have small seeds and be short with soft strings, be turgid and tender. The width of the pods should be between 6-9 mm while the length of 12-l4 cm is recommended.

• Bobby beans comprise beans of marketable quality which do not qualify for inclusion in the higher classes but satisfy the minimum requirements specified above. Beans should be reasonably tender and seeds should not be too large.

• N/B: In all grades, the pods should have the characteristic size and colour of its variety.

Packaging, Pre-cooling and Transportation

• The pods are packaged in corrugated fiberboard cartons of 3 kg gross weight or in plastic pre-packs weighing 250,500 or 1,000gm.

• The pods are pre-cooled to remove field heat. This is done at 7-80C (using forced air coolers). The beans can be stored at 7 to 80C and a relative humidity of 95­-100% for up

• The cartons should be carefully stacked during transportation to reduce movement of cartons and allow free movement of air. Insulated or refrigerated vehicles should be used for transportation of french beans.

Post harvest diseases

• White mold can infest pods just before harvesting and cause damage to the crop during storage and transportation. This can lead to loss of an entire shipment. The losses are highest at temperature between 18 and 240C.

• Hydro cooling of beans in chlorine water after sorting and maintaining temperatures in shipping container at 3.3-4.4 ⁰C helps reduces the post-harvest losses.

Challenges in production

• A major setback is rejection of the produce if they do not meet the set quality standards. (Harvest as per the buyers specifications of pods)

• Poor disease and pest management can lead to poor quality produce

Advice to Potential Growers

• With continued demand for the beans being recognized, export companies are going into contract farming with farmers. This involves setting of fixed prices that run throughout the year whether the season is low or high.

• Due to high labour requirements it is recommended that it is grown on a small scale, possibly with staggered planting so that a manageable proportion of the crop is ready for picking at any one time and that harvesting is continuous. For instance, the land may be divided into convenient sized plots (i.e. ¼ acre plots) and planted at 2-3 weeks intervals.

• Growing these beans requires a lot of dedication and capital especially for the high season. The most sensitive stages in production include; germination, flowering, fruiting and harvesting.