Asian melons

24.05.17

Overview

Asian melons are members of the Cucurbitaceae family and are termed Asian melons as they are widely used in Asian cuisine. They originated from Indo-China and have spread throughout Asia.

The Asian melons group includes the following species:

  • Luffa aegyptiaca — smooth luffa, sponge luffa or sponge gourd (sze qua)
  • Luffa acutangula — angled luffa, silk gourd or Chinese okra (sin qua)
  • several types within the species Benincasa hispida:
    • winter melon  or wax melon (dong qua or tung gwa)
    • hairy melon (chia qua)
    • long melon (opo squash)
  • Momordica charantia — bitter melon or bitter gourd (fu qua).

Bitter melon is the most commonly grown Asian melon in Australia and further information on this crop can be found in the Bitter melon entry on this website.

All species of Asian melons are climbing annual herbs with long, thick, hairy stems with simple lobed leaves. All melons except the winter melon are grown on light trellises, winter melons, being quite heavy (3–4 kilograms) can be grown on the ground.

All the melon types are consumed as immature fruits either in stir fries, soups or curries. Fruits of the smooth luffa must be harvested at a young stage to be edible, if left to fully ripen, the fruit is very fibrous and is used as a scrubbing sponge for bathrooms, kitchens and cosmetic purposes.

The Asian melon industry in Australia is classified as an emerging industry and is represented by the industry association AusVeg. In the Northern Territory, Asian vegetables, including bitter melon, are also represented by the Northern Territory Farmers Association and the Northern Territory Vietnamese Horticultural Association (NTVFA).

Facts and figures

  • Asian melons are members of the Cucurbitaceae plant family
  • They  are grown in hot humid climates
  • The Northern Territory is the major region producing Asian melons in Australia
  • Production practices are similar to other cucurbit crops — most are grown on mounds and trellises
  • Harvest timing of Asian melon is critical to ensure optimum quality
  • Harvesting Asian melons is labour intensive
  • Australian production of Asian melons is consumed entirely domestically as fresh produce
  • Luffas can be grown to maturity to be used as sponges but there is limited production of this type in Australia

Production status

Publicly available production figures for Asian melons in Australia are difficult to obtain. In the Northern Territory, the major production area in Australia, the production of long melons generally exceeds luffas, which exceeds winter melon. Prices vary greatly depending on the quality of the product and seasonality of the supply.

As at 2014 there was no importation or exportation of Asian melons from Australia.

Map of current and potential growing regions

Uses

Winter melon can be used green or mature. Young fruit can be used whole, especially in curries. The

mature fruit can be stuffed and baked whole or have the skin removed and the flesh used in soups or sugared to become candy.

Hairy and long melons are also consumed immature in a similar way to winter melons.

When picked early (less than 12 centimetres in length) luffa fruits are usually cooked or fried and used in soups or sliced and dried for later use. Very small fruits can be eaten raw or pickled.

Mature fruits of the smooth luffa are washed to remove the rind and remaining flesh. The remaining fibrous material is then dried and treated to be used as sponges. They are commonly used in bath products in Australia but have been used in Asia as pot scrubbers, in mats, slippers and mattress stuffing, and they can even be used as engine filters!

Production Requirements

Growing regions

Asian melons are mainly produced in the Northern Territory during the winter months and in other states in the warmer months. The main production area is near Darwin where melons are harvested from May to October. Two crops per year are possible in the warmer climates. Asian melons are also grown in Western Australia and in the Northern Rivers district of New South Wales from January to April.

Soil type

Asian melons can grow on a variety of soil types but prefer soils with good organic content and neutral pH (commonly around 6.5). They also require free draining soils to avoid waterlogging.

Climate

Asian melons are subtropical or tropical in nature and optimum temperature for their production is between 25 to 27°C, they can tolerate higher temperatures but growth is slowed in temperatures below 18°C. Irrigation is necessary in the dry season in the Northern Territory.

Most of the Asian melons are not frost hardy and they may also suffer from waterlogging. Winter melon is quite drought tolerant.

Varieties

Hairy melon (chia qua) are staples of the Chinese diet and have a mild flavour similar to zucchini. They are generally 20–25cm long, cylindrical fruit and the skin is green with fine hair covering the rind. The presence of hair is a sign of freshness.

Winter melon (dong qua) is closely related to hairy melon (chia qua). It is a large round to oblong melon, similar in size to a watermelon, and the skin is green with white blotches on it, which are caused by a natural wax covering. It also has a mild flavour, like zucchini. Different cultivars are used to produce mature or immature fruit and producers in the Northern Territory use open-pollinated (pollination through birds, bees and insects) varieties. To produce a mature fruit can take up to five months.

Long melon or opo squash is also closely related to hairy melon. This melon is thin, long and cylindrical similar to cucumber, and it has a mild taste like zucchini.

Smooth luffa, sponge luffa or sponge gourd (sze qua) is a large green and cylindrical fruit with a smooth slightly ribbed skin with pale stripes. It has a mild flavour and slightly spongy texture.

Angled luffa, silk gourd or Chinese okra (sin qua) is a long slender fruit 15–40cm in length with 10 deep ridges running from end to end. It has a mild flavour and slightly spongy texture.

Traditionally, angled luffa has been used for vegetable production whilst smooth or sponge luffa has been used for sponge cleaning products due to its more fibrous nature.

It is difficult to source seed of Asian melons within Australia and local companies may source seed from Asian seed companies. Farmers usually grow open pollinated varieties and save the seed.

Planting and crop management

Winter melons are either grown from seed or from seedlings that have been pre-germinated on a hot bed. Use of transplant seedlings can result in shorter time to harvest but it is much more labour intensive.

Winter melons can be grown at high densities on trellising but are usually grown prostrate on mounds on the ground at lower densities as they produce quite large fruits. Producers in the Northern Territory that grow winter melons on the ground, have 60–80cm between plants and 1.5 metres between rows. This density requires about 2kg/ha of seed but higher densities can be used if growing the melons on trellises. The mounds may be covered with mulch or plastic for weed control and moisture retention. Production on mounds can also prevent waterlogging. Winter melons need a lot of organic matter and some nitrogen–phosphorus–potassium (NPK) fertiliser at planting plus some side-banded nitrogen until flowering. While winter melons are drought tolerant; maximum production is achieved with irrigation in regions with low rainfall.

Agronomic requirements for hairy melon are essentially the same as for winter melon, as the two melons are variations of the same species. Note the use of trellising can produce more uniform fruit, prevent wind rub damage, prevent the fruit touching the ground and developing fruit rot and discolouring. Trellising ensures uniform growth of the melons as they hang down and it has been observed that trellising can also produce larger fruit.

Luffas, like the hairy and winter melons, are grown on trellises placed on mounds of soil. The trellises are usually about 2m high. Smooth luffa can be planted in a rectangular system 100cm by 100cm, while angled luffa can be planted up to 20cm closer. Both crops are best grown on trellising, though angled luffa can be grown prostrate. Luffas need a lot of NPK fertiliser plus side banding of nitrogen up to flowering. However, it should be noted that too much nitrogen in combination with high temperatures encourages excess male flowers thus reducing yields. Luffas are not drought tolerant and need irrigation in dry periods. Smooth luffas are more resistant to waterlogging than angled luffas.

As all the Asian melons are cucurbits they have male and female flowers, and the presence of bees greatly assists pollination and fruit set. The proportion of female flowers may increase with cooler and shorter days. Spraying of insecticides should be carefully monitored so as not to affect the crop pollinators.

For further information on planting and crop management of bitter melon refer to the RIRDC New Crop Industries Handbook and the Northern Territory Department of Primary Industry, Fisheries and Mines Fact Sheet Asian Melons.

Weeds, pests and diseases

Both luffas and winter melons are relatively insensitive to most pests and diseases, however powdery mildew and downy mildew may cause problems if left uncontrolled. The major insect pests are fruit flies and aphids. Cucurbits are susceptible to viruses and aphid control is important as they are vectors of various viruses. Nematodes, particularly root knot nematodes can affect all of these melons and it is important to use a crop rotation with non-susceptible crops, use of an off-season green manure crop may also help in the management of nematodes. Some growers plant alternate rows in their cropping systems to provide a break for soil health benefits.

Winter melon is particularly robust against disease and is sometimes used as rootstock for other cucurbit crops.

No pesticides or herbicides are specifically registered for use on Asian melons in Australia, however off-label use permits are available. It is necessary to check with the relevant state department for current permits.

For further information on diseases and insect pest of cucurbits and their management refer to the NSW DPI Primefacts Diseases of cucurbit vegetables  and Insect pests of cucurbit vegetables  and the RIRDC New Crop Industries Handbook.

Infrastructure Requirements

Infrastructure requirements for the production of Asian melons include a tractor and some type of bed former, trellis materials, irrigation and spray equipment and cooling and a cool storage facility for the fruit after harvest.

Harvesting & Processing

All the Asian melons are harvested by hand up to twice a week when they are ready for market. Fruit should have a fresh appearance and be of uniform colour and size, immature fruit should have low seed development.

Winter melons may be picked immature or fully mature. Melons picked early need to be used quickly, as they have a shelf life of about three weeks; however if picked when fully mature they have a long storage life at 13–15°C in a dry atmosphere.

Immature winter melons are picked about 3–4 weeks after fruit set when they are 10–12cm long. Although the melons can grow up to 40kg these melons are usually picked at 1.5kg. Overgrown melons can be picked at maturity but they are of lower value and are usually used in soups, hotpots or casseroles.

Winter melons should be wiped free of dust but the wax should be left on the fruit. Immature melons are packed into pawpaw boxes, so they are not touching one another and have a shelf life of three weeks. Mature melons are packed into half tonne bins on pallets and should be packed lower than the top of the bin to prevent freight damage. Winter melons are more difficult to pack as they are round rather than long like the other melons.

Hairy melons are preferred small, solid and green. The hairy surface of hairy melon should not be washed off as it is a gauge of the melon’s freshness. The fruit should be stored carefully at around 10–12.5°C as it is susceptible to chilling injury, the packaging should be well ventilated to avoid the build-up of ethylene which can enhance ripening of the fruit.

Luffas need to be handled gently if they are to be picked for eating. It is important to remove the field heat from the melons as rapidly as possible once they have been picked; the retained field heat may be reduced if the melons are picked in the cool of the day. The melons can be stored for 2–3 weeks at 12–16°C.

Sponges are harvested from smooth luffas at maturity, 4–5 months after planting. Smooth luffas can produce up to 20–25 fruits per plant whilst angled luffas can produce 12–20. Both types of melons weigh between 0.2–0.8kg per fruit.

If processing a luffa to produce a sponge, the fruit is immersed in water until the rind dissolves and the pulp and seeds are washed out. The remaining fibrous material is bleached with hydrogen peroxide and dried in the sun.

Markets & Marketing

The largest Asian melon markets are in Sydney and Melbourne where the highest populations of people who have Asian-influenced diets are based. All Asian melons produced in Australia are consumed domestically.

Risks & Regulations

Risks/challenges

The main risks for producing Asian melons are the selection of planting material, the timing of harvest, establishing a market for the product, and within and between season price fluctuations. The latter are caused primarily by fluctuations in supply. While some of these challenges are common for many vegetable crops, they can be more significant issues for new growers. Careful planning and understanding of existing markets before planting will increase the success of melon production.

Regulatory considerations

The standard regulatory considerations that apply to all Australian farms, including laws applying to chemical use and management, occupational health and safety and transport (including machinery movements and the loading/unloading of harvested product), apply to Asian melon operations.

Some producers of Asian melons choose to participate in Freshcare, which is currently the largest Australian on-farm assurance program for fresh produce for on-farm food safety and quality and environmental certification services.

When processing raw product into value-added food products, consideration should be given to food standards regulations. Further information can be found at the websites of FreshcareHACCP and Food Standards Australia New Zealand.

Quarantine issues may need to be addressed if Asian melons are marketed interstate.

Another regulatory consideration relates to the use of pesticides as there are currently no pesticides registered for use on Asian melons in Australia, however off-label use permits are available. It is necessary to check with the relevant state department for current permits.

Publications

Publications/ information products

Emerging animal and plant industries: Their value to Australia RIRDC publication (2014)

Diseases of cucurbit vegetables  NSW I&I PrimeFact no. 832 (2009)

Insect pests of cucurbit vegetables  NSW I&I PrimeFact no. 833 (2009)

Sin qua Luffa acutanula NSW DPI Factsheet (2005)

New Crop Industries Handbook RIRDC Publication (2004)

Asian melons Northern Territory Government Fact Sheet (2003)

Winter Melon CQ University

Luffas CQ University

Other resources

Freshcare is an industry owned, not-for-profit on-farm assurance program, established and maintained to service the Australian fresh produce industry.

HACCP Australia  is a leading food science organisation specialising in the HACCP Food Safety Methodology and its applications within the food and related non-food industries.

Food Standards Australia New Zealand is a bi-national Government agency. It develops and administers the Australia New Zealand Food Standards Code, which lists requirements for foods such as additives, food safety, labelling and GM foods. Enforcement and interpretation of the Code is the responsibility of state and territory departments and food agencies within Australia and New Zealand.

Industry Bodies

AusVeg is the national peak industry body representing the interests of Australian vegetable and potato growers and is committed to securing the industry’s future.

Northern Territory Farmers Association is the peak body for the Plant Industry in the Northern Territory and is an amalgam of the former Northern Territory Agricultural and Horticultural Associations.