Recently arrived pest costs growers millions

30-08-2010 | Alan Emerson

>Growers and orchardists are pouring millions of dollars into controlling the adverse effects of the recently arrived tomato-potato psyllid (TPP) insect and its death-dealing bacterium.

First detected in New Zealand in 2006, TPP has spread throughout the North Island and the east coast of the South Island, carrying a virulent Candidata liberibacter which can kill the plant or tree rapidly.

It occurs on solenaceous plants of the tomato and potato family which include common weeds such as black nightshade, cape gooseberry, morning glory and convolvulus.

Potato growers now spend their entire annual research and development levy on the pest and their organisation has called for a voluntary levy of $1/tonne to boost its efforts.

However, the highest costs of TPP to potato growers are felt on the ground with additional management costs of $700/ha average or $7 million annually nationwide.

Product prices haven't risen to pay for the necessity to spray insecticides so often.

Constant vigilance is required.

Experimentally it has been found that just one "hot" pysllid (bacteria-infected) feeding on a potato plant for one hour transfers liberibacter sufficient to slash tuber yield and create "zebra chip" (ZC) in potatoes used for processing.

Tamarillo growers have been flattened by the liberibacter, losing large numbers of trees which has cut this year's autumn-winter fruit harvest volume by more than 50%.

Exports have been sharply curtailed as growers struggle to satisfy local market demand.

Once infected, a tamarillo tree must be ripped out and replaced, which means a one to two year wait for more fruit.

Indoor tomato and capsicum growers say they are learning to live with the insect and its bacterial threat but only at the cost of their integrated pest management (IPM) programmes which have been interrupted by TPP outbreaks and the need for urgent sprays.

Fresh Tomato group chairman Wim Zwart said considerable money goes into monitoring and management and the search for biological controls.

MAF biosecurity exports team manager Karen Sparrow said the TPP incursion has been one of the biggest issues for her team in recent years.

Because NZ was one of the first countries to get TPP and liberibacter outside of its native United States, reaction was quick against our fruit and produce exports in countries which did not have TPP.

Australia suspended tomato, capsicum and tamarillo imports which dragged down prices on the NZ market.

Japan halted capsicum imports and the big Fijian market for fresh potatoes was interrupted.

Although market access has been restored in most countries, methyl bromide fumigation is now necessary for truss tomatoes and tamarillos into Australia.

Dairy farmers concerned about where grain price will go

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