Some of Australia’s major growers of citrus fruit are demanding urgent action in the Northern Territory to prevent a disease outbreak that is spreading south and west from Darwin and threatens to ruin the $750 million industry.
In effect, the growers want all citrus trees in the restricted area and control areas in the NT and WA destroyed immediately, with owner reimbursement and compensation paid. This might save the 28,000 ha of trees in the rest of the country that may be in the path of the outbreak of Asiatic citrus canker.
The latest outbreak has been confirmed at several plant nursery sites in and around Darwin, as well as in Kununurra in WA. In the last 48 hours, there have been reports the infestation has moved south, past Adelaide River and into Katherine, more than 300 km from Darwin.
Asiatic citrus canker is a contagious bacterial disease that causes unsightly lesions on fruit, its leaves and stems, reducing their appeal to the markets. Trees infected with the disease may suffer from low vigour and a reduction in fruit quality and quantity. Canker can affect limes, lemons, citron, mandarins, oranges and grapefruit.
The disease spreads rapidly, particularly in tropical and subtropical climates, by wind-blown rain, overhead irrigation systems, birds, vehicles and through people moving infected plant material or equipment. That makes all commercial growing areas vulnerable to attack.
Urgent action needs to take place now, as the cyclone season is only months away.
The disease is widespread in many tropical and subtropical citrus-growing areas of the world, but, until now, Australia has had a market advantage in that each time it has been detected here, it has been eradicated, usually by drastic action.
Australia has had seven outbreaks of citrus canker in the last 100 years and each time it has been eradicated.
In 2004, an outbreak of citrus canker at one property near Emerald in Queensland eventually resulted in all citrus trees within a 50-km radius being destroyed as a precautionary measure. This growing district had 500,000 trees.
Initially, authorities had adopted a “cookie cutter” approach, excising circles of trees within a 600-metre radius of plants known to be infected. When that was found to be inadequate, the more drastic 50-km reduction zone measure was adopted. But it worked. The disease was eradicated and, after two years, orchards were replanted but the economic cost to some individual growers was in the tens of millions of dollars.
That is why today growers are alarmed at the potential of the latest NT nursery outbreak to once again decimate the industry. They want the same action taken now as in Emerald in 2004 – discard the cookie cutter option and destroy all host plants in the NT before the disease has a chance to spread.
Yet, so far it has already taken plant health authorities four weeks to confirm the NT outbreak, twice as long as in 2004.
According to some growers there is a code of silence in place that involves plant health authorities and even the industry’s peak body, Citrus Australia, because it cannot or will not reveal to growers the full impact of the outbreak. Citrus Australia is effectively gagged through its membership of Plant Health Australia’s Emergency Plant Pest Response Deed (EPPRD).
There is a complete lack of urgency to keep growers fully informed.
Craig Pressler is the chief operating officer of 2PH, a 1000-ha citrus farm at Emerald. The family business this year is celebrating its 50th year in operation. The 2004 outbreak emanated from a property eight kilometres away and resulted in 2PH having to destroy 200,000 trees, wait for two years and then replant at its own cost.
“Since that time, little has happened in terms of contingency plans across the industry,” Pressler says. “A draft contingency plan is still just that, a draft, 14 years after the last outbreak.
“Seed and budwood stock can be imported into Australia legally. However, plant material has been introduced illegally but there have been no prosecutions.”
He says the citrus nursery industry has to be regulated. Australia is the only country in the world in which there are no regulations on nurseries producing citrus.
“We all suspect that budwood has been illegally imported here.”
Pressler says that in signing the EPPRD, Citrus Australia has its hands tied in speaking publicly about the extent of the pest problem. The real fear of growers for the future of their industry is that there is a general outbreak and canker will become endemic.
There have been many thousands of trees sent to NSW, Qld and SA and this tracking information has not been released to industry.
“The issue is that unless there have been thorough and intensive traces through the supply chain as on-the-ground inspections and other actions as necessary, this will be the major catalyst to hurtling Australia into an endemic classification for all citrus grown in Australia,” he says.
“Many countries in the world will not take imports from canker countries. This could be the death of citrus growing in Australia.”
Pressler says authorities are trying to portray the latest outbreak as an urban problem, not a commercial problem, because it has been detected in plant nurseries in Darwin and Palmerston and in a backyard tree in Katherine.
“That does not diminish the threat, the clear danger that it can be brought to commercial farms,” he says.
“The cookie-cutter zone control (600-metre radius) is totally inadequate. The only solution for the future of the industry in Australia is to remove all trees in the whole affected area and to do it now. By a decision being delayed, it means the risk of greater infection is increased.
“The biggest farm in the NT is 20,000 trees; there are perhaps 100,000 in the whole of the territory. We have more than twice that on this one property alone in Emerald.
“It is essential that the NT be neutralised now.
“If citrus canker becomes endemic in Australia, that is, part of the natural order, we will lose our overseas markets. Many countries will not import fruit from places where canker is established.”
Citrus is the nation’s largest fresh fruit export industry. In 2017 export earnings rose 41 per cent to $462 million with China the major market.
Australia’s major production regions are in the Riverland, the Murray Valley, the Riverina and the Central Burnett region in Queensland as well as some plantings in WA, inland and coastal NSW and the Northern Territory.
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