Seed rate: this varies greatly, according mainly to variety. Some examples, in kg/ha:
Canadian Wonder 55–70, pole snap beans 22–34, bush snap beans 56–170. There
are approximately 2000–5000 seeds per kg.
Seed spacing: 5–23 cm between plants, 52–90 cm between rows.
Depth: 2.5–5.0 cm in heavier soil, 5–10 cm in light soil.
Inoculation: generally not necessary. The common “Cowpea Group” of rhizobia are
often ineffective on Phaseolus species.
GROWTH CONDITIONS
Day length: French bean plants respond to day length according to species and sub-
species. Most climbing types are either long-day or short-day, most bush types are
day-neutral.
Growth period: 60–150 days for mature, dry seed; 45–75 days for green pods.
Temperature: optimum is 16–24
plant is killed by frost. Maximum is about 30 C.
Rainfall: haricots can produce a reasonable crop with 400 mm rainfall per year if
the rain is well distributed. They benefit from some rain at flowering and seed-set,
and dry weather for harvest of dry beans. Yields start to decrease when rainfall
exceeds 1500 mm, due to both flower drop and increased disease damage.
Altitude: approximate range, in msl: tropics 600–1950, Kenya 900–1500, Ethiopia
1650–1950.
Pests: in the tropics, pests are usually the main limiting factor to growing haricot
beans:
- Aphids—cause damage by both sucking the plant sap and by transmitting virus
diseases. Black aphids are often the worst, causing yellowing and distortion of the
leaves.
insecticides.
- Bean Leaf Beetle—the larvae attack the roots, the adults attack the leaves and
stems.
(hypocotyl). Control is best by seed dressings, and also with early planting, rotation
and the removal or destruction of volunteers and infected plants.
- White Flies—found mainly in Central and South America, they also transmit viral
diseases. - Bean Pod Weevil—the seed is attacked in the pod.
resistance in some varieties, otherwise insecticides may become necessary.
- American (Cotton) Bollworm—mainly in Africa. Round holes are bored into the
seed pods. - Spotted Borer—the larvae, which are olive-green and hairy and have rows of
dark spots, eat the seed inside the pod. Difficult to control.
disease.
° °
°
C. Growth stops altogether at c.10 C, and the- Bean Flies—very common in Africa. Stems crack and distort at the base
- Mexican Bean Beetle—these eat the leaves, and are easily controlled with
- Potato Leaf Hopper and Green Leaf Hopper—plants are stunted. Some
- Spiny Bugs—cause damage by sucking plant sap, and also transmit a fungal