Rural Industries Research & Development Corporation

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Introduction

The scarcity of information on the production statistics of these vegetables in Asian economies reflects the relatively small-scale nature of such industries and their meagre contribution to the agricultural economy of many Asian countries. However, this does not detract from the significant role they play in the diet and livelihood of local communities, particularly in South-east and south Asia. The incomplete statistics shown in Table 2 (not available in this html version) iare gleaned from various sources. Two interesting trends can be seen: a) an increasing demand for these vegetables in Asia and b) the relative importance and increasing demand for bitter gourd and snake beans over the other fruit-type vegetables.

Marketing issues

The size of the Asian vegetables industry in the Northern Territory in 1996 is listed at $3.5 million and is forecast to increase to $8 million by the year 2000. Sixty percent of this value is contributed by the vegetables listed here which have increased two-fold in value since 1995 (Table 3 - not available in this html version). The range of prices (per kg) received by growers varies according to the markets and is as follows: bitter melon $2-3.50; hairy gourd $2-3.50; wax gourd (long type) $1-2; winter melon $1.50-3; snake gourd $2-3 (local market); and snake beans $2-3.50. There are currently 42 Asian vegetable growers in the Northern Territory, from less than ten four years ago. The majority are Vietnamese, followed in descending order of magnitude by Thais, Indonesians, Filipinos, Europeans and Malaysians.

The following strengths and weaknesses could apply to the whole Asian vegetables industry and not merely to loofahs, gourds and snake beans. The strengths include:

• good spread of growing season in different areas

• consistent seasonal supply from growing regions

• counter-seasonal to northern hemisphere Asian markets

• good domestic market demand

• good opportunities for import substitution and export to Asian markets

• Northern Territory's proximity to Asian markets

• clean green image

• industry levy for research and development and the weaknesses include:

• fragmented, small, intensive farm units

• lack of cohesion and coordination in production and marketing

• long distance transport from northern production areas

• lack of efficient cool chain

• under-capitalised farm operations

• continuous ravages from pests and diseases

• poor understanding of English by many growers

• short shelf-life of produce

• continuous intensive production decreases sustainability

• lack of research and development funding in appropriate regions of production.

Production requirements

Loofahs are frost-sensitive and are more suitable for the lowland humid tropics. They prefer sandy loamy soils with a
pH 6.5-7.5, rich in organic matter with good drainage. Heavy rain during flowering and fruiting is harmful. In this respect, areas around Darwin with generally eight months of dry weather are admirably suitable for the loofahs. Also, excessive nitrogen fertilisers can reduce female flower numbers.

Bitter melons thrive on well-drained, sandy loam soils rich in organic matter. They do not like water-logged areas, are tolerant of a wide range of environment and will grow at up to 1000 m altitude.

Snake beans prefer a day temperature of 25-35°C and a night temperature not below 15°C. They prefer soil with pH 5.5-7.5, and can grow on sandy soil if given good irrigation as they need plenty of water.

Varieties

Growers obtain their seeds from vegetable wholesalers in Melbourne and Sydney. Most are not aware of the cultivar identity although they are aware of the existence of varieties in the market.
 

Agronomy

Planting distances employed by growers are as follows:

• loofahs—40-60 cm by
1.5-2 m between rows

• wax, winter and hairy gourds 60-80 cm by 1.5 m between rows

• bitter melons 50 cm, 1 m between rows

• snake gourd 60 cm, 1.5 m between rows

• snake bean single row on ridges or on raised 1.2-1.5 m wide beds with double rows planted 60-90 cm between rows and 40 cm between plants.

On acidic soils with pH 5-6, as found around Darwin, it is recommended that the soil be limed with 200-300 g/m²
2-3 weeks before planting. This should be followed by a basal dressing of a high analysis, NPK fertiliser (N = 10-16: P = 10-16, K = 10-16) and single superphosphate. Both have to be applied at the rate of 70 g/m² worked into the rows a week before planting. The NPK fertiliser is also applied every two weeks at 40-50 g/plant throughout the season. Additionally 2-4 kg of well-rotted, organic manure or compost should be split-applied several times during the growing period. Foliar fertilisers can be sprayed onto the plants 3-4 times during the growing season to rectify and ensure adequate supply of micronutrients: for example, sodium molybdate
1 g/L, zinc sulphate 2 g/L, iron sulphate 2 g/L mixed with low biuret urea at 5 g/L and 1 mL/L of a wetting agent. Boron should be foliar applied separately as Solubor—1 g/L before flowering and fruiting, or soil drenched around the plant at 2-4 g/L.

Pest and diseases

The most important pests that attack snake beans are: thrips (Thrips palmi), bean fly, caterpillars, crickets, mites, root knot nematodes and parrots. The important diseases of beans are leaf rust (Uromyces phaseoli) and fruit anthracnose.

The best way to control pest and diseases is to use integrated pest management (IPM). In IPM, all available methods, cultural, physical, biological and chemical, are employed together in a sound compatible way to manage the pest population. IPM will result in reduced chemical use by promoting a more judicious and safer way of applying chemicals. For instance by using `softer' chemicals like potassium soaps, light summer oils, or pheromones. Another example is to use off-season sorghum crops as green manure coupled with crop rotation to manage the root-knot nematode problem. Also for all vegetable crops it is essential that growers observe the safe withholding periods for the chemicals.

Harvesting and storage

The loofahs are harvested at the half-mature stage, 9-13 weeks after planting, as the mature stage is too fibrous. The fruits can be stored for 3 weeks at
12-15°C.

Snake gourds are picked 3-4 weeks after fruit set when they are green, tender, immature and 30-70 cm long. They store well for 2-3 weeks at 15-18°C under high humidity.

Bitter melons are harvested 3-4 weeks after fruit set when they reach marketable age, light-green, thick and juicy, 11-30 cm by 4-7 cm in diameter and not at the ripe mature, yellow-orange stage. They keep only for 2-3 days at ambient temperature but at 5°C they store for 3 weeks.

Snake beans are harvested while immature, 6-8 weeks after planting. They store well at
8-10°C for 4 weeks. Harvesting is carried out 2-3 times a week during the 6-8 weeks season.

Key contacts

Key references

Nguyen, V.Q. 1992 Growing Asian Vegetables Agfact H8.1.37.

Pan, C. 1996 Fresh and Processed Asian Vegetables RIRDC Research Paper No. 95/14.

Vinning, G. 1996 Market Compendium of Asian Vegetables RIRDC Research Paper No. 95/12.

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