Growing fresh runner and dwarf beans in Western Australia

Growing the crop

Planting

Times of planting and production in the different areas are shown in Table 1.

Plant every two to four weeks to obtain a succession of harvesting periods. Plant by hand or by machine, 3 to 4cm deep.

Depending on season, beans will emerge in 5 to 14 days. Do not thin the seedlings.

Climbing beans

Space climbing beans in single or double lines per row. In single lines, space at 15 to 25cm, with two seeds at each site and 1.0 to 1.3m between the rows. If planted in two lines per row, plant 0.6m between the lines and 1.5m between the rows, with two seeds planted every 30 to 40cm. About 40kg of seed per hectare is required.

Dwarf beans

With dwarf beans, aim for a plant population of 30 to 40 plants per square metre. About 45kg of seed will be needed per hectare. Plant rows 50cm apart with single seeds spaced at 7.5 to 10cm.

In Carnarvon, plant in rows 1.2m apart with two lines 60cm apart per row and two seeds planted every 15cm.

Beans for mechanical harvesting are planted with rows 30cm apart and 50 to 75cm between seeds in the row. Seeding rates are around 90kg/ha.

Watering

Most growers use overhead sprinklers in Perth and the south-west. This has the advantages of cooling plants in hot weather and increasing the humidity around plants. Trickle irrigation can also be used, especially in Carnarvon, and leads to large savings in water, weeding and labour. Growers in Carnarvon use a combination of low volume trickle watering (1.5 to 2.0L per hour per dripper) and black polythene mulch, 0.9 to 1.2m wide.

Beans require moist soil at all times but must not be waterlogged, especially for the first week after planting. Do not overwater for the first month after planting, as this can result in excessive vegetative growth.

Increase watering from two weeks before flowering to two weeks after flowering. As a guide, irrigate as shown in Table 2 from flowering onwards.

Fertilisers

Nitrogen is the main fertiliser needed, although some nitrogen is supplied to the plants from Rhizobium bacteria in nodules on the roots. Plants short of nitrogen are stunted, with small pale green leaves. Excess nitrogen will produce too many leaves and lower yields.

Beans also need phosphorus and potassium. Plants low in phosphorus have small, dark green leaves turning to bronze, with some defoliation and poor flowering. Plants short of potassium have stunted growth, with curled yellowish leaves and scorched leaf margins.

To improve soil organic carbon levels, apply compost at 30 to 50 cubic metres per hectare sometime in the rotation. This will supply organic matter, add nutrients and help retain moisture in the soil.

Analyse soil and irrigation water before planting, plus one to two analyses of the youngest mature leaves during the first half of the growing season. This 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.

In Perth and the Swan Coastal Plain, apply the following rates of magnesium and trace elements before planting:

• 50kg/ha magnesium sulphate to supply magnesium
• 20kg/ha manganese sulphate to supply manganese
• 18kg/ha borax to supply boron
• 18kg/ha iron 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.

South-west

• On heavier textured soils such and loams and gravelly loams, phosphorus requirements should be applied based on soil test results and banded at sowing. Some potassium and a small amount of nitrogen may also be banded at sowing. Seek advice from DAFWA advisers or your horticultural consultant regarding a specific fertiliser program.

Perth

• On sands with yellow subsoil, apply phosphorus before planting according to soil test. Phosphorus fertilisers may be broadcast and incorporated.
• A simple fertiliser program on sands is to follow with weekly dressings of 50kg/ha urea and 70kg/ha of sulphate of potash.

Carnarvon

In Carnarvon, the soil and irrigation water supply adequate levels of potash. Apply fertiliser as follows:

• Apply double superphosphate at 1.5kg per 60m row and incorporate into the soil to 15cm before planting, if soil test phosphorus is less than 100mg/kg.
• Apply urea at 1kg per 60m row one week after emergence and again at the same rate just prior to flowering. Sulphate of ammonia (2.1kg per row) can also be used.

Trellising

Climbing beans require support from the four leaf stage onward, using one of the following systems:

1. Place vertical stakes (25mm square and 2m long) every 30 to 50cm.
2. Use ti-tree (Melaleuca uncinata) stakes, 2 to 2.25m high. Dip the bottom 45cm of the stake in tar to prevent rotting. The stakes form an inverted ‘V’ trellis and are supported by a central wire 1.6 to 1.8m high.

Where Fusarium disease has caused damage in previous years, dip stakes in a bath containing sodium hypochlorite (1% chlorine) for ten minutes, two weeks before use. Wash excess soil off the stakes before dipping them.

Four to six weeks after planting, it may be necessary to assist some of the plants to climb around the sticks in an anti-clockwise direction.