Walnut industry expansion

Summary

Global awareness of the health benefits of nuts, including walnuts, is driving an increased demand for nuts and nut products. Presently, walnuts are planted from Tasmania to Moree in northern New South Wales (NSW). There are small production regions scattered throughout northern Victoria and southern NSW, and the Adelaide Hills and Riverland regions of South Australia (SA).

Large walnut orchards are located in the Goulburn Valley (Victoria), Riverina (NSW) and Tasmania. There has been strong growth in the Australian walnut industry over the last decade, with projections for continued growth. The Australian Walnut Industry Association (AWIA) is the representative association for small and large walnut orchards, which presently cover approximately 3,000 ha of walnut plantings throughout Australia (ANIC 2015).

The Australian industry is relatively disease and pest free (compared with other global industries), which increases the marketability of Australian grown walnuts. Large walnut industries are located in the Northern Hemisphere, for example California, with only 3% of the world’s production coming from the Southern Hemisphere in 2008 (ANIC, 2015). The Australian walnut industry has room to expand and provide the freshest nuts for six months of the year.

Walnuts (Juglans regia L.) grow up to 25 to 30 m tall and can live for hundreds of years. Native to Central Asia, they prefer a Mediterranean climate with cold winters and mild summers. A walnut tree is first harvestable after 4 to 6 years and reaches full productivity by 11 or12 years of age. Trees are wind pollinated over 2 or 3 weeks of pollination; they are self-compatible, but pollination and flower receptivity often fail to synchronise and pollinators need to be interspersed throughout the orchard (Adem, 2004). Walnut trees produce male catkins and female pistillate flowers.

Traditionally, the cultivars planted in Australia were terminal bearing; more recently there has been an increase in cultivation of lateral-bearing varieties, many of which are imported from California. Pollination occurs during spring and nuts are harvested in April or May. The edible nut, or walnut kernel, is contained within a hard wrinkled shell that grows inside a leathery green husk. Hull split occurs late in the growing season and trees are shaken for mechanical harvesting.

This information package is supplementary to high resolution maps available online. The information provided should be used as a guide to narrow down potential regions for expansion, however, specific site analysis should precede any expansion. A further use of this work would be to provide information of suitable regions for sentinel plantings to determine the most appropriate regions for expansion of the Australian Walnut industry.