Citrus rootstock projects bear fruit for our Industry

A decades-long citrus rootstock project is bearing fruit for Australia and its international partner countries.  Successful rootstock selections from ACIAR trials were formally released to industry yesterday in Sydney.

A trifoliate orange with small, felty fruit, can be used as a root-stock for grafting to provide a drought tolerant tree

For the last thirty years ACIAR has collaborated with Australian state agricultural departments, industry peak bodies, and our Asian partner countries to improve citrus varieties, protect against diseases and orchard management. We have worked with countries including China, Pakistan, Bhutan, Indonesia, Vietnam and Thailand.

 Graeme Sanderson evaluates new citrus varieties in Bhutan

 ‘Much of the Australian benefit derives from evaluating new varieties to exploit new market opportunities, at home and overseas, and new rootstocks to address production issues,’ explained Dr Richard Markham, ACIAR’s Research Program Manager for Horticulture. ‘ACIAR projects in several countries have contributed to this work over some twenty years.’

The best citrus Chinese rootstock selections from ACIAR trials were formally released to industry at the New South Wales Parliament House, Sydney, on 10 May 2017.  Dr John Dixon, Research Program Manager for the Cropping Systems and Economics program, represented ACIAR at the event.

Representatives from the New South Wales Department of Primary Industries (DPI) - which has the largest citrus research and extension team in Australia, Citrus Australia - the industry’s peak body, and the People’s Republic of China also attended.

Citrus planting material for the industry is multiplied, free of pests and diseases, by Auscitrus

ACIAR has evaluated Chinese citrus genetic material in New South Wales for 16 years, and rootstock from other Asian countries since 1987.

‘Rootstocks are important both for treeform but particularly for disease resistance,’ Dr Markham said.  ‘The profitability and viability of the industry depend on having a pipeline of new genetics coming through, both new varieties and the rootstocks to support them.’

Dareton Research Station maintains one of the world’s most diverse and comprehensive collections of citrus root-stocks

Four orange (Citrus trifoliata) and two Chinese mandarins that performed well in South Australian trials will be commercially released in Australia in mid-2017.  A new mandarin rootstock named after Patricia Barkley, the NSW DPI citrus pathologist who brought rootstock materials from China in the 1990s, was revealed at a field day in Gayndah, Queensland, in March.

The Australian citrus industry is the largest fruit exporter in Australia, worth more than A$200 million a year.  It produced 492,000 tonnes of citrus in 2013, primarily navel and Valencia oranges (79%, or 389,799 tonnes) and mandarins (18.5%, or 91,000 tonnes).  Australia exported 158,000 tonnes of oranges to 30 countries and 50,000 tonnes of mandarins in 2015.

Three trees in one: a trifoliate orange (with ‘fluted’ trunk) provides the hardy roots, a Valencia orange the trunk (and ‘compatibility’ with other citrus varieties) and a mandarin grafted on top contributes the leaves, flowers and fruits.

NSW alone produces 40% of Australian citrus and 36% of citrus exports a year.

ACIAR research continues to work with Asian partners to understand a potential new threat to the Australian industry, the bacterium Huanglongbing which is spreading through South East Asia.  HLB, also known as citrus greening disease, threatens citrus production worldwide, but has not yet reached Australia.  

‘The biggest threat in the world at the moment to Australia’s citrus industry is from HLB,’ said Dr Markham.  ‘Because of the work with ACIAR and the industry, we’re as ready for it as anyone will ever be.’