French beans are the immature green pods of phaseolus vulgaris grown mainly for both domestic and export markert in Kenya
Varieties
Fresh market varieties: Army, Pekara, Teresa, Paulista, Rexas, Samanatha and Cupvert
Export varieties: Army, Teresa, Samantha, Julia, Tokai and Baraka
Processing varieties: Julia, Vernandon and Sasa
Ecological requirements
Altitude: 1000-2000m above sea level
Rainfall: 900-1200 mm annually, irrigation is essential for continuous production during the dry spell.
Soils: fertile and well drained silty loam to heavy clay soils with ph 6.0-6.8
Temperature: 20-250C
Land preparation
Prepare land early, remove weeds especially the perennials and other obstacles in the soil. Harrow the field to a fine tilth desirable for French bean production.
Planting
The crop is grown all year round under irrigation, planted 2-3 weeks interval. Single row spacing should be 50cm by 10cm, double row at 60cm by 30cm by 10cm. and one seed per hole. Seed rate range from 50-75kg per hectare depending on seed size of selected variety and spacing.
Fertilizer and manure application
At planting apply 200kg DAP and 10 tons of organic manure. Top dress with 100kg CAN in a split application.
Trellising/plant training
Its essential for the climbing varieties. Poles or other means of support at least 200cm high.
Weed control
Keep the field weed free throughout the growing period. Should be done shallowly to avoid root destruction. Avoid weeding at flowering stage as this may lead to flower knock down
Pest management
Bean fly: Seed dressing, spray with suitable insecticide
Bean thrips: Foliar spray with diazol before flowering and during flowering with decis
Aphids: Use appropriate insecticide eg match or duduthrin
Red spider mite: Practice field hygiene, spray with appropriate insecticide
Cut worms: Use suitable insecticide eg karate
Root knot nematodes: practice crop rotation, fallow farming, soil drench with nematicides eg mocap
Disease management
Leaf Rust: crop rotation, use suitable fungicides eg baycor before flowering and farmcozeb during flowering
Angular leaf spot: use certified seeds, seed dressing, spray with copper hydroxide or baycor
Root rots: Seed dressing, drench with brassicol
Bacterial blights:Use certified seeds, practice field hygiene, crop rotation, spray using copper based fungicides eg kocide
Anthracnose: Use certified seeds, field hygiene, crop rotation, resistant varieties, spray with suitable fungicide eg daconil
Bean common mosaic virus: Use certified seeds, field hygiene and control of vectors
Bean golden mosaic: Strict crop rotation program, good field hygiene, use certified seeds, control vector eg silver white fly
Harvesting
Picking of pods begins 6-8 weeks after planting and continues for 1-2 months. Picked pods must have the stalk attached to them. If picked wet the produce should be placed on clean cloth, under shade to dry before packing. Yield range from 9-12 tons per hectare
Post-harvest handling
Harvested pods should be protected from direct sun. Sort out to remove broken, malformed, overgrown, off-types and insect-damaged pods.
Grading
- Extra fine pods: very tender, turgid, seedless and without strings. The pods should be less than 6mm width and minimum length of 10cm
- Fine pods: have small seeds, soft strings, turgid and tender. Pods width of 6-9mm and length of 12-14cm
- Bobby beans: beans of marketable quality but not inclusion in the high class. Must be of reasonable tender and seed not too large.
Packaging and storage
Pack the pods in corrugated fiberboard cartons of 3kg gross weight or in plastic pre-packs weighing 250-1000g. Pre-cool the pods and store at 7-8C and R.H of 95%-100% for 1-2 weeks