The Australian Macadamia Society represents the biosecurity interests of macadamia producers and the industry.
In 2013–14, macadamia production was valued at $108 million (LVP). There are around 18,000 hectares planted with macadamias in Australia, comprising approximately 5.5 million trees. Annual production is approximately 45,000 tonnes in-shell or 15,000 tonnes of kernel.
The significant majority of plantings are varieties of Macadamia integrifolia. Of these about 80 per cent are Hawaiian selections with the remainder being Australian varieties. Harvest commences in March and runs through to August.
Australian macadamia production stretches from Coffs Harbour on the NSW north coast to Mackay on the north Queensland coast. The majority of macadamia plantings are in northern NSW and south east Queensland. The northern rivers region of NSW is the largest production area comprising about 45 per cent of production. The fastest growth in production is occurring in the Bundaberg area which currently represents around 35 per cent of production.
Approximately 70 per cent of the crop is exported, principally to Europe, USA, Japan, China and other Asian countries. Australia is currently the world’s largest producer of macadamia kernel and second largest producer overall. South Africa and Kenya are the other major producers.
In order to encourage biosecurity awareness within the industry, approximately 70 per cent of orchards employ professional pest scouts and the Australian Macadamia Society convenes an annual pest scout forum where pest pressures for the previous season are reviewed and any new pest and disease sightings reported.
Macadamia trees (Macadamia intergrifolia and M. tetraphylla) are tall evergreen trees growing to 20 m in height. The flowers are 5–10 mm long and are born on racemes with 100–150 flowers. There are about 2,500 flowers on a tree. Each flower has 20 ovules, four anthers attached to the petals, and a long stigma. It takes about a week for all the flowers on a raceme to open, with most opening over 2 days. Most cultivars are partly or completely self-incompatible so inter-planting with compatible cultivars is usually necessary. Cross pollination has been reported to increase nut weight as well as the number of nuts. Nut set in Australia and New Zealand is usually less than 1 per cent. A three-year study of macadamia pollination in Queensland, Australia found pollination to be a limiting factor.
In Australia, macadamia will start flowering in August and September. The flowers produce both pollen and nectar. The anthers dehisce several days before the flower opens and the sigma only becomes viable after the flower opens. Flowers are visited by a range of insects including honey bees. Most honey bees collect nectar in the morning and some honey bees collect pollen in the afternoon. The flowers are attractive to bees for 3 days after opening. Each flower produces relatively small amounts of nectar. The pollen gatherers are reported to be better pollinators than nectar foragers as they are more likely to contact the stigma. Since the macadamia is native to Australia, the flowers are also visited by native stingless bee and solitary bees such as Trigona sp. However, as stingless bees are only managed on a small scale, honey bees and unmanaged stingless bees are probably the most important pollinators of macadamia. It has been estimated that about 150 bee visits to a racemes are needed for full pollination in Australia.
The optimal number of bee hives per ha is 5 to 8 based on research from both in Australia and overseas. As pollen collectors are more effective pollinators than nectar foragers, colonies should be managed to promote pollen collection eg high brood to bee ratios, sugar syrup feeding and pollen trapping or stripping.
Additional fact sheets and web links about the pollination of this crop are listed below. Please be aware that some of the information was developed overseas, and environmental and seasonal variations may occur.
Macadamia pollination fact sheet, The Pollination Program (Rural Industries Research and Development Corporation and Horticulture Australia Limited)
The effect of supplementary pollination on nut set of macadamia, University of Queensland and CSIRO research paper, Annals of Botany
Successful bee management tips for during flowering pest management, Australian Macadamia Society
Bees and the pollination of macadamia, University of the Sunshine Coast
|Annual value of macadamia production 2007–14 (LVP)|
|Distribution of macadamia production by state and territory 2013–14 (based on LVP)|
The pollination information is an excerpt from Mark Goodwin (2012) Pollination of Crops in Australia and New Zealand. RIRDC Publication No. 12/059
The industry overview and graphs on the value of production and crop distribution are from the National Plant Biosecurity Status Report (2015), Plant Health Australia, Canberra