Durian

24.05.17

Durian (Durio zibethinus) is known as the King of Fruits and is the most highly prized fruit in Southeast Asia. Revered in Asia for its exquisite flavour and taste, its overpowering and distinctive odour makes it less popular in Western countries and cuisine.

Overview

Durian is an evergreen, tropical native tree of Southeast Asia and thrives in a hot, humid tropical climate. Originally thought to have come from the Indonesian Malay archipelago, with Borneo a major centre of origin, it is now extensively cultivated in Thailand, Malaysia, Indonesia and Cambodia. Durian trees can grow to 20m tall with a diameter of 8–10m within 15–20 years.

While currently a small exotic tropical fruit industry in northern Queensland and the Northern Territory, it is thought that durian has potential to be developed into a viable fruit crop in northern Australia, to satisfy domestic demand for fresh fruit.

The Australian industry faces many challenges. Major problems include highly variable production dependent on seasonal conditions, tree and fruit disease management, and identification of internal fruit quality.

Production is estimated at around 60 tonnes with an estimated gross value of AU$480,000. However, cyclones Larry (2006) and Yasi (2011) destroyed many durian trees in north Queensland requiring a restocking of tree crops.

Durian was introduced into tropical north Queensland in the 1970s but is regarded as a developing industry, and its interests are represented by the Rare Fruits Association and the Sub-tropical Fruit Club of Queensland.

Facts and figures

Durian, known as the King of Fruits, is the most highly prized fruit in Southeast Asia
It is not as popular in Western cuisine due to its distinctive odour
Durian is grown in north Queensland and the Northern Territory
Production is estimated at around 60 tonnes with an estimated gross value of AU$480,000
Many trees were destroyed by Cyclones Larry (2006) and Yasi (2011)
Durian has the potential to be developed into a viable specialist small holder crop for northern Australia

Production status

Commercial growing of durian fruit commenced in the Northern Territory and north Queensland in the 1970s. Over 60% of durian production occurs in the Northern Territory, with Queensland accounting for the remainder.

Before Cyclone Larry in early 2006, there were 36 durian growers in Australia with around 13,000 trees. The cyclone inflicted widespread damage and although there have been re-plantings, there were only around 5,000 durian trees in Australia in 2011–12.

Based on tree numbers and average yields, durian production in Australia in is estimated at around 60 tonnes, with an estimated gross value of AU$480,000.

There were small quantities of Australian exports of durian in the past but almost none in the 2000s. There are larger quantities of imports, all provided by Thailand and Malaysia. Market access for frozen durian was granted to Thailand and Malaysia in 1999 and 2004, respectively, after import risk assessments.

Map of current and potential growing regions

Uses

Durian flesh is mostly prized as a fresh fruit but is also a popular flavouring for ice-cream, jams, desserts and cakes.

The richness of the flesh also makes an excellent addition to hot, spicy foods such as curries and chilli dishes. Durian can be canned and dried and the seeds can be roasted and eaten like nuts.

Production Requirements

Growing regions

The climate in northern Queensland is conducive to the cultivation of durian, especially around Cairns to Cape Tribulation. In northern Queensland, plantings were found along the coastal strip from Tully north to Cape Tribulation, however many of these trees were destroyed during cyclones Larry (2006) and Yasi (2011).

Durian is grown in the distinct wet/dry monsoonal climate of the Northern Territory around Darwin but does not do well in Katherine or in Kununurra in northern and Western Australia. The long dry seasons experienced in this region with extended periods of low relative humidity are not ideal for a crop native to the humid equatorial tropics.

Soil type

Durian trees prefer deep, well-drained fertile soils, high in organic matter. They thrive on deep sandy clay loams in far north Queensland.

Climate

Durian thrives in hot, humid, high rainfall, tropical environments, with a temperature range of minimum 23°C and maximum 33°C.

It needs evenly distributed, annual rainfall of 2,000–3,000mm, however it grows in the 1,600mm annual rainfall, of the wet–dry topics around Darwin, where rainfall is supplemented with irrigation.

The main limiting factor for durian is the duration of the cold temperature and low relative humidity as cool and dry conditions are detrimental to photosynthesis and active growth.

Varieties

Australia has one of the most comprehensive collections of durian clones due to the past efforts of state agriculture departments and private collectors. The bulk of this material is in the hands of producers. In Australia, durian tend to be grown from up to a dozen main cloned varieties that were introduced into northern Australia at different times. There are still seedling based orchards which produce fruit of variable quality.

The introduction of new clonal material is a challenge because of restricted access to material from overseas and a lack of suitable tropically based post entry quarantine facilities. Initial work has been undertaken to evaluate varieties for adaptability and productivity in an Australian context.

Planting and crop management

Site preparation will vary depending on growing location. However, it is generally accepted that in high rainfall areas, trees should be grown on mounded soil to protect them against Phytophthora disease, which thrives in waterlogged soils.

If growing durian in a windy region, a permanent natural windbreak should be established before planting. Jackfruit (Artocarpus heterophyllus) is another exotic tropical fruit tree that may be useful to consider as a windbreak, as it will also provide orchard income. Otherwise, contact your local department of primary industries or forestry to determine which species will suit your region.

Clean nursery stock should be sourced from a specialist nursery, which produces advanced planting material (trees six to twelve months old).

Spacing of trees ranges from 6-10m within the row and 8-12m between rows, depending on variety selected, growing environment and land availability. Newly planted trees should be protected with shade cloth surrounds until they are at least two years old and young trees may benefit from the use of plastic covers during the cooler winter months.

Trees should be mulched with non-compacting straw (e.g. sugar cane or spear grass), which remains well aerated under wet conditions. Application of regular small amounts of a well-composted chicken or alternative manure may be beneficial.

Durian flowers are borne on the main branches (ramiflorous) and very occasionally on the main trunk (cauliflorous). Pruning practices aim to build a canopy composed of a vertical trunk with well spaced horizontal orientated branches. When trees are 2–4 years old, some pruning should be carried out to open up the canopy and remove any vertically orientated branches. Heading trees at 3-4m is now a management practice in Southeast Asia. Minimal pruning is required on mature, fruit bearing trees.

The dry season of the Northern Territory can pose a risk to durian, as they are extremely sensitive to low humidity and soil moisture conditions. Little is known about the crop water requirements of the durian, and different varieties have different tolerances to drought, but irrigation during the dry season will be necessary. In the Northern Territory, irrigation rates of up to 2,000 litres per tree per week, for trees 8m in diameter, from September to November have been recommended.

Durian is a shallow rooted tree with 60% of the total root length confined within 60cm of the crown and 0–30cm from the soil surface, therefore it is recommended that frequent watering in small amounts is more beneficial than applying large amounts of water infrequently. Mulching trees can also help to conserve soil moisture.

Durian need a nutrient rich, fertile soil but very little is understood about durian nutrient demand and fertiliser rates used by growers are ad hoc and subjective. Generally fertiliser is applied just after harvest, prior to flowering and during fruit development. Soil and leaf survey guidelines and analysis for north Queensland are discussed in the AgriFutures Australia reports, Boosting Durian Productivity and Durian Germplasm Evaluation. Growers should consult local advisers and are encouraged to adapt fertiliser inputs to regular leaf and soil analysis and yield records to achieve best results for their location.

First fruit can be expected 5–7 years following planting, with regular production occurring from 7–10 years and onwards.

Weeds, pests, and diseases

Durian can suffer significant crop damage from fruit spotting bugs, mealy bugs, fruit fly, caterpillars, red-banded thrips, swarming beetles and stem girdling borers. Please check the Pubcris Database on the Australian Pesticides and Veterinary Medicines Authority website to see if there are any chemicals are either registered or permitted for your specific crop or more generally for your crop grouping e.g. durian specifically or tropical fruit more generally. Once you have found the chemicals listed, view the label and follow the instructions according to the label.

Phytophthora is the most serious disease of durian that causes dieback, root rot, patch canker and pre and post harvest fruit rots. Currently the use of potassium phosphonate as a trunk injection or foliar spray is recommended. Potassium phosphonate is a plant defence regulator, rather than a fungicide.

Infrastructure Requirements

The existing infrastructure on most established horticultural enterprises would suit durian production. This includes an irrigation system, as well as cleaning, sorting, packing and refrigeration infrastructure. Note however, that durian is not suited to automated or mechanical processing equipment so cleaning, packing and sorting has to be done by hand.

Durian, like many exotic tropical trees, benefit from shading when young, therefore frames or stakes supporting shade cloth may be necessary.

Fruit picking infrastructure may include a hydraulic ladder to pick physiologically mature green fruit and/or tarpaulins or nets which are used in parts of Malaysia to catch ripe fruit as it falls during harvest months. This will reduce damage to fallen fruit.

If growing durian in cyclone prone regions, an investigation of trellising or alternative infrastructure to support trees in high winds is recommended.

Harvesting & Processing

Harvest times are November to February in the Northern Territory and January to April in north Queensland.

Fruit are best picked when physiologically mature, prior to being tree ripe when they drop from the tree. Tree ripened and fallen fruit are more likely to suffer physical damage and an increased incidence of postharvest rots compared to picked fruit. In parts of Southeast Asia, particularly Penang in Malaysia, tarpaulins or nets are erected below the tree during the ripening months. In other areas, a string is attached from the branch to the peduncle (stalk) below the abscission layer to prevent the fruit from falling after abscission occurs. In Thailand, fruit are picked physiologically mature and allowed to ripen under controlled conditions or during transit to buyers. Fruit contact with the ground is avoided to reduce the incidence of postharvest disease.

Ripe fruit has a short shelf life of between 2–3 days but storing at 5–10°C can extend the shelf life by several days. Harvesting mature green fruit is based on understanding a range of maturity indices. These include: calendar date, swelling of the stalk abscission zone, skin colour, spine density and audio response to fruit tapping. Experience using these maturing indices is required.

Fruit can be harvested before it is ripe and stored at 15°C, which will extend shelf life to three weeks. A range of semi and fully processed products can be made from durian. In Southeast Asia, fresh cut product (aril with seed packed in cling wrapped styrofoam trays) and blast frozen flesh are popular products.

More work is needed on post-harvest handling of durian, particularly to mitigate the strong odour, which can restrict options for air and road transport to southern markets. Fruit are sometimes double boxed to help contain the odour as the fruit ripen in transit.

At this stage, durian are packed on farm and sold to consolidators, wholesalers or directly to retail outlets, where they are on-sold, utilised in the food service industry or processed for other uses.

Markets & Marketing

Durian production in Australia is estimated at around 60 tonnes with an estimated gross value of AU$480,000.

Exotic tropical fruit is considered a small niche industry and the fruit is currently grown in small quantities, therefore marketing can be a challenge. Durian is rarely grown as a mono-crop and is usually part of a multi tropical fruit farming system. Hence, growers have a number of income sources for cash flow. The small production base of durian ensures that marketing is rarely a problem with eager demand from local and interstate markets. Because of the exotic and specialist appeal of the crop it is an industry that could easily develop marketing challenges if the market was to be over supplied. When planning to market any horticultural product, it is important to remember that wholesalers and retailers are generally looking for the following attributes from a supplier:

well presented fruit
a great tasting product
high quality flesh texture
on-time delivery and consistency of supply.

The need for on-time delivery and consistency of supply, usually at high volumes, can hamper exotic tropical fruit producers from actively participating in the larger horticultural market. This has been a particular challenge for growers in North Queensland recovering from cyclones Larry and Yasi, where a large part of the exotic tropical fruit industry was destroyed. Those growers who have decided to re-plant and are harvesting fruit from their remaining trees have noted the difficulty in supplying consistent volumes large enough to justify transport costs or attract wholesalers. As a result, many growers are marketing at a local level, for example selling at farmers markets or directly to restaurants. Some growers are investigating tourism opportunities through farm tours or farm gate sales. Research is also underway into potential value add opportunities for exotic tropical fruit.

For durian in particular, the strong odour is perhaps the greatest barrier to marketability, both in the restricted options in air and road transport, but also in finding acceptance in new markets where consumers with no experience of the fruit are unable to reconcile the odour with a quality product.

The supply chain for tropical fruit provides a useful framework for industry entrants to understand the potential marketing structure. It should be noted that while the supply chain is relatively short, the diverse array of participants and the need to move fruit quickly before it deteriorates, does add some complexity.

A typical supply chain for tropical fruit has the following linkages:

grower
packer
transporter
unloading agent
wholesaler/agent
(potentially a secondary wholesaler)
processor
exporter
retailer

chain retailer (e.g. major supermarket)
specialist retailer (e.g. a fruit and vegetable shop)
foodservice (e.g. a restaurant)

consumer.

These are not necessarily listed as a sequential supply chain, for example some growers will bypass packers and wholesalers and sell directly to restaurants or consumers. Wholesalers will also sell to secondary wholesalers, who in turn on-sell to smaller retail buyers and providers who may supply the food service industry.

Traditionally, wholesale ‘central’ markets in capital cities were the major way to sell and distribute horticultural products. Supermarket and other retail buyers would visit and buy produce required, based on available supply. Now the large supermarket chains such as Coles and Woolworths often prefer to deal directly with growers who produce larger volumes or alternatively with packers or agents who consolidate produce from a number of growers to ensure consistent supply.

Factors affecting the price are seasonal availability, the availability of substitute products and consumer spending and preferences. Premium produce will generally earn a premium price, however, there are no guarantees of this always happening. For example an oversupply of high quality fruit will depress prices but equally, periods of low availability will see even average quality fruit command high prices.

It is often suggested that one of the best ways to monitor price signals and plan production accordingly is the establishment of good business relationships between the grower and the wholesaler/agent. This can add some transparency around market signals.

Risks & Regulations

Risks/challenges

Like all tree crops, the biggest commercial risk to new entrants to the industry is the length of time between planting and the first harvest (5-7 years). Add to this that many exotic tropical fruit trees require significant upfront investment (for example, irrigation and trellising infrastructure), intensive management and a significant investment of time and energy, a return on investment may take even longer to achieve.

For durian, commercial risk is heightened by the fact that the knowledge of the management practices needed to underpin a productive durian industry in Australia is still being developed. The interaction of vegetative phases to floral initiation and the impact of fertiliser and irrigation scheduling, pruning practices to carbohydrate partitioning, flowering and fruiting is not well understood. One, or any combination of these factors, can result in poor fruit production.

The transfer of knowledge is hampered by a lack of information about the exact durian varieties currently in production in Australia. Some of the named durian clones introduced into northern Australia were incorrectly identified and may not represent the authentic clones from their original sources in Southeast Asia. This confusion about varieties could lead to incorrect management practices and consumer dissatisfaction in the marketplace.

Durian are particularly susceptible to a range of pests and diseases. Phytophthora palmivora and Pythium spp. can be devastating to durian and significant crop damage occurs from fruit spotting bugs, mealy bugs and stem girdling borers.

Durian has a strong odour and this can restrict the options for transporting them to southern markets. More work on packaging options of fresh durian to eliminate the odour during long distance air or road transport is required.

Tropical cyclones pose a considerable risk to primary industries in far north Queensland and the Northern Territory. Cyclones Larry (2006) and Yasi (2011) devastated production areas of far north Queensland around the towns of Innisfail, Tully and Cardwell and inland regions of the southern Atherton Tablelands.

In the aftermath of Cyclone Yasi, a number of Queensland growers left the tropical tree fruit industry. While an understanding of the lessons learned by these cyclone events has been documented, research into cyclone preparedness is still underway with a range of management options, like trellising of fruit trees, being investigated. Since the cyclones, securing affordable insurance is a major challenge to growers in cyclone prone regions with some insurers declining to offer insurance at all.

Regulatory considerations

Before buying new land to plant orchards, a thorough investigation of the land’s suitability for a horticultural enterprise and its cropping or land use history, should be undertaken. This may include identifying a history of chemical contamination (and residue levels) as some export licences may be withheld on products grown on land where chemical residues exist. Potential disease risks should also be investigated. Some disease pathogens can survive in the soil for many years, so information about previous disease outbreaks will assist determining which trees are suitable for planting. This information can generally be obtained from the relevant state planning authority.

Growers will also be responsible for regularly inspecting their orchards for notifiable pests and diseases, particularly durian seed borer, and reporting any incidence to the relevant state agriculture department.

When planting new orchards and establishing additional on-farm infrastructure or access roads, liaison with the state government agencies responsible for planning, native vegetation laws and water licences will be necessary. Some land use applications will also need to be considered by the relevant local government authority.

Horticulture and food production businesses have strict requirements in relation to record keeping, registrations, and accreditations as well associated costs for e.g. quality assurance, food safety, safe use of chemicals, environmental performance and intellectual property. Websites like Freshcare may provide a starting point for understanding these requirements.