Avocado addicts who despair about the high prices of their favourite fruit won't see instant relief.

Supplies of avocados are at their lowest ebb in late autumn and early winter, and the boom and bust nature of growing means prices have gone as high as $6.99 this month.

In 2016-17 the harvest was 7.9 million trays but the volume tumbled last year to only 3.8 million trays. Avocados crop well only every two years.

Meantime some countries are awash with them. Mexico grows about a third of world production for 12 months a year compared to New Zealand where growth peaks in October-November, and exports large quantities.

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At present New Zealand imports no avocados but some of the world's biggest growers - Mexico, Peru and Chile - are sizing up the possibilities of exporting them to New Zealand following the signing of  the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP) deal.

New season avocados have just started to appear in stores but are in short supply.

Avocado NZ chief executive Jen Scoular said New Zealand had never been closed to imports but no countries had ever shown an interest because the market was so small.

"New Zealand has just not been on their radar. Mexico needs countries like the United States which takes 30 times New Zealand's production."

Australia was a larger priority because it was a bigger market, and Chile had already started talks across the Tasman to gain access.

Up until five years ago New Zealand had been a low price market except for a small window in autumn when values shot up because of scarcity.

Exporting countries also have to go through hoops to gain market access. Scoular said it took four years for New Zealand to get permission to export to China, a market which opened up just this year.

"The only restrictions are they have to meet phytosanitary and biosecurity requirements. They have to go through obtaining an import health standard, which involves a pest risk analysis."

"If there are pests which may be a problem, the exporting country has to say how they will guarantee none of the pests will be on produce coming across our border," Scoular said.

Between them John Greensmith and Tony Gibbs are planting up 110 hectares of avocados at Tapora, near Kaipara Harbour.

The US banned Mexican avocados in 1914 over fears of an insect infestation and did not lift the ban until the North American Free Trade Agreement was signed in 1994.

From February onwards until the export season begins in spring no New Zealand avocados are exported, so the price is not governed by what consumers pay in overseas markets.

About 65 per cent are exported, 25 per cent are consumed by Kiwis, and the remainder is processed. Most (80 per cent) exports are to Australia, but Asia is increasing its imports of New Zealand fruit.

Executive general manager for T&G in New Zealand Andrew Keaney said the pricing for avocados was determined by supply and demand. T&G is one of the country's biggest sellers of wholesale fruit and vegetables.

"New Zealand's main avocado season runs from September through to April. The reason fruit is expensive now is purely because we are out of season and supply is scarce, with only a small number of shoulder season growers able to deliver avocados to markets and retailers."

"Pricing should stabilise in the next two to three months however as new season fruit is picked and makes its way into stores," Keaney said.

US President Donald Trump has proposed a 20 per cent tax on all imported goods from Mexico to pay for the border wall between the United States and Mexico. Avocados are a key Mexican export.

Demand for avocados had increased significantly over the past five years.

As a result avocado growing was ramping up. Main centres of growing are Northland and the Bay of Plenty.

Last year Harbour Edge Avocados bought a 405-hectare dairy farm on the shores of Kaipara Harbour to convert into an orchard, with plans to plant 100,000 trees producing 5000 tonnes a year.

In the same area EZY Peel Mandarin owner and former corporate heavyweight, Tony Gibbs, and former Fresh Food Exports owner, John Greensmith, have both set up avocado enterprises.

Altogether in Northland an estimated 850 hectares of orchards are underway or scheduled for development. Scoular welcomed them, saying by 2021 there would be about 20 per cent more land in avocados than today.

"Without a doubt more supply will be good for consumers but predicting volumes in the current season is difficult enough, let alone in a few years' time."

She said while people may regard prices as high, they were prepared to pay the same for a cup of coffee in a cafe, and an avocado had much greater nutritional value.

 - Stuff