Fungicides Provide Significant Financial Benefits to Australian Macadamia Producers International Pesticide Benefits Case Study No. 79, May 2013

Australia is the home of the macadamia nut. Australia accounts for about one-third of world production. Macadamias are grown along the eastern seaboard of New South Wales and Queensland. About 13,000 tonnes of kernels are produced in a normal year from 6 million macadamia trees on 18,000 hectares. Exports with a value of $120 million account for about 70 % of Australian production. Husk spot caused by Pseudocercospora macadamiae is a serious disease affecting macadamia in Australia. Husk spot has not been reported from any other macadamia producing nation. Husk spot has spread from Queensland where it was first reported in 1981 to all production areas in south-east Australia. [1]. The edible macadamia kernels are contained inside a hard shell surrounded by a fibrous husk. Infection of the husk by the fungus gives rise to characteristic tan-brown lesions on the surface. The spores adhere to the husk, germinate and penetrate the host through openings (stomata). In the absence of effective control, about 15 % of the total annual value of macadamia production in Australia would be lost [3]. A major part of the economic impact is caused by premature frui