Growing the crop
Planting
Plant two or three times at about three-week intervals from late April to June so that harvesting is spread out. Broad beans take 14 to 20 weeks to reach maturity.
Crops planted too early in summer and early autumn will grow tall and flowers may not set at the top of the plant until September. As a result, yields will be low and the crop will take a long time to mature. Crops planted too late will also produce low yields and will be affected by high temperatures in late spring.
Sow the seeds 12 to 15cm apart in single rows 80cm apart, about 2.5 to 5.0cm deep.
Broad beans produce less well in windy areas. Double rows — 20cm apart with 1m between the double row centres — help the plants withstand wind and a windbreak will also reduce wind damage.
Keep plants well watered.
Fertilisers
The broad bean is not a heavy feeder and, being a legume, will produce some of the nitrogen it needs from bacteria in nodules on the roots. Acidic soils — less than pHCa 5.3 — should be limed to improve root nodulation.
Applying compost at up to 30 cubic metres/ha to other crops in the rotation will supply organic matter, add nutrients and help to retain moisture in the soil.
Before planting, apply magnesium and the following trace elements in the annual program:
- 50kg/ha magnesium sulphate to supply magnesium
- 20kg/ha manganese sulphate to supply manganese
- 18kg/ha borax to supply boron
- 18kg/ha ferrous sulphate to supply iron
- 18kg/ha copper sulphate to supply copper
- 18kg/ha zinc sulphate to supply zinc
- 2kg/ha sodium molybdate to supply molybdenum.
Apply phosphorus requirements before planting.
One week after planting, side-dress fortnightly with nitrogen such as urea at 15kg/ha and sulphate of potash at 30kg/ha. Too much nitrogen may lead to too much leaf and low yields.
Nutrient analysis of the soil and irrigation water before planting, plus one to two analyses of the youngest mature leaves after planting, will enable some adjustments to the fertiliser program and provide information on nutrients that are deficient or toxic.
Some of the suggested nutrients may be deleted or reduced if they are sufficiently high in the irrigation water and soil, including sources from compost and fertilisers from previous cropping.
Do not apply excess fertilisers because nitrogen, phosphorus and potassium are easily washed through sandy soils by rainfall and irrigation. This may lead to pollution of surface and groundwater.
Weed, pest and disease management
The registration and availability of chemicals for weed, disease and pest control change regularly. Consult a trained and experienced horticultural agronomist or the Australian Pesticides and Veterinary Medicines Authority (APVMA) website for chemicals which are currently registered or have a permit for use on this crop. The information on the label or permit for a chemical must be followed, including the directions for use, critical use comments, withholding period and maximum residue limit. Quality assurance (QA) schemes for horticultural crop production require producers to have current information on chemical registrations and permits at their fingertips. The information to be found at this website allows this requirement to be met.
Weeds
Broad beans are good competitors with weeds.
Pests
Aphids, snails, caterpillars (pods), redlegged earth mite (seedlings), vegetable weevil and nematodes are common pests.
Disease
Chocolate spot (Botrytis fabae) can cause extensive losses and is the major disease in Western Australia. This is seed-borne and crops may also be infected by wind-borne spores from residues of previous crops. Chocolate spot spores can survive in the soil for several years and there should be a rotation of at least two years before broad beans are grown on the same ground.
Chocolate spot usually appears as small reddish brown leaf spots in late winter to spring. The disease spreads most rapidly under humid or wet conditions in spring. Chocolate spot may be introduced into new bean growing areas by sowing infected seed.