The tree is large and spreading in habit, growing slowly to about 25m tall, long-lived and deciduous. It produces fruit that has a green leathery husk, containing a hard wrinkled shell. The kernel of the nut, or nutmeat, is made up of two halves, the appearance of which resembles a brain.
The kernels have a wide variety of uses as a food. Walnuts can be eaten raw, toasted or pickled; prepared with sweet or savoury flavourings as a snack; and used whole or chopped in bakery goods, breakfast cereals, salads, soups, meat dishes, confectionery and ice-cream. Oil, flour and meal are also produced from walnut kernels.
Although walnuts had been grown in Australia for over 100 years, the industry remained small and production in 2002 was 150t (in-shell). Research in Victoria, reported in 2000, showed that production could be increased through applying amelioration techniques to shallow, poorly-structured soils; irrigating to meet water requirements by using soil moisture monitoring techniques, and using grafted trees and new high yielding varieties.
The new varieties introduced could bear fruit in their first year and mechanical harvesting and commercial yields were possible by about years 4–6, however, full production was not reached until years 10–12.
From the 1990s onwards several changes occurred within the industry. The Australian Walnut Industry Association undertook to investigate a means of industry expansion and developed a fee-for-service consultancy as a means of generating R&D funds for industry advancement; also several large walnut plantations were established. In-shell production has increased to around 6,000t. Extensive plantings by corporate interests around 2010 are predicted to lift future production levels to around 16,000t by about 2021. Based on current plantings, 90% of national production will be from one company.
The interests of walnut growers and promotion and development of the industry is conducted on behalf of the industry by the Australian Walnut Industry Association.
Facts and figures
- The walnut tree most familiar to Australia, in backyards and commercial plantations, is the English or Persian walnut (Juglans regia)
- Walnut trees are a temperate species, requiring distinct cold and warm periods through the year
- While modern varieties of walnut bear fruit within their first few years, it takes 4–6 years to produce a harvestable quantity and 10–12 years for the tree to reach full production
- The work load for walnut growers is intensive during spring and autumn, but as the trees are dormant through winter they require little attention during these months
- About 3,500 hectares are planted to walnuts in Australia
- There is growing consumer demand for walnuts overseas and domestically, believed to be in response to publicity of results of nutritional studies that demonstrate the health benefits of walnuts and the expansion of cultural influences on food via the media.
- Market opportunities for new growers are influenced by scale of production and ability to meet market demand, with export markets requiring significant volumes and domestic markets seeking fresh ‘direct from the grower’ product
The area planted to walnuts in Australia is about 3,500 hectares, with around 2,200ha belonging to one company with operations in Tasmania and New South Wales. Australian production is around 6,000t in-shell but this is expected to increase to over 16,000t when all current plantings reach full production by around 2021.
By volume, the key production regions are the Riverina in New South Wales and the east coast of Tasmania. However, walnuts are also grown throughout Victoria, in cooler regions of southern New South Wales around Adelaide and the Riverland, and in south west Western Australia.
The industry comprises family farm operations of small, sometimes older orchards and large, new orchards that are managed by a few companies, where orchards are a combination of joint venture, investor funded, private ownership or company-owned entities.