WELLINGTON (NYTIMES) - The popular breakfast of avocado toast is under threat in New Zealand, with two years of low harvests generating waiting lists for avocado trees at garden centres and inspiring a rash of thefts from orchards.

Official figures showed that local avocado prices smashed records in May. The average cost of the fruit has risen to NZ$5 (S$4.50) per avocado, a 37 per cent increase over last year.

Because of its strict biosecurity laws, New Zealand does not import avocados, and growers say the fruit's short supply and increasing popularity has led some to take desperate measures.

Ms Jen Scoular, chief executive of the industry body New Zealand Avocado, said the thefts were mostly "opportunistic", as criminals saw a way to make money from the shortage.

An avocado black market has sprung up to distribute the spoils, with the sunny, fruit-growing region of Bay of Plenty particularly hard hit, police officials said.

"It's not like cannabis, where people can say it was for their own personal use," said Mr Alasdair Macmillan, New Zealand's coordinator of community policing.

"It's clearly not for their own consumption," he said. "You can only put so much avocado on your burger or in your sushi."

Some of the thieves did not appear to be criminal masterminds. Mr Macmillan said two were caught fleeing an orchard carrying duvet covers loaded with US$4,300 (S$5,900) worth of avocados each.

But other thefts showed more extensive planning.

One recent case involved thieves who parked a station wagon inside an orchard, in a corner of the property that was not regularly visited, before filling backpacks with the plundered fruit.

Last month, a grower in the upper New Zealand region of Northland said 70 per cent of his avocados had been stolen, a loss worth US$66,000.

The grower, Mr Graham Burgess, told The New Zealand Herald that the theft was "pointless" because the fruit was months from being ready to harvest and would go to waste.

Mr Macmillan said he knew of "half a dozen" cases that resulted in charges.

But he said gathering evidence could prove difficult, since some crops are checked only every few weeks and growers might not know when a theft had occurred.

"So already the investigation cycle has been slow to begin, and the baddies get three or four weeks' head start," he said.

"The evidence would be well and truly devoured by then."

Some frustrated growers have taken matters into their own hands.

Last November, someone surrounded an avocado tree in New Zealand's largest city Auckland with razor wire, drawing concerns from neighbours who feared children or cats could be hurt.

"Is a child's health really worth a few avocados?" one resident asked, according to the website Stuff.

Mr Bret Glazer, who lives in the Auckland suburb of Sandringham, recently spent more than US$500 on a security system for his avocado tree after multiple thefts.

The 9m tree produces 500 avocados a season, most of which Mr Glazer gives away to neighbours, workmates and friends. Last year, it was "professionally harvested" of several hundred fruit in one night, he said.

In April, Mr Glazer's partner caught two thieves red-handed - "older men," he said - as they tried to strip the tree, wielding a long stick with a hook on the end for reaching the upper branches. When confronted, he said, they fled, one of them on a mobility scooter.

Ms Scoular said most of the illicit fruit probably ended up in small fruit stores or sushi shops, or was used in food service.

Law-abiding citizens, meanwhile, have deluged garden centres with requests for avocado trees, often having to settle for being put on a waiting list.

Mr Andrew Grilli, store manager at The Plant Depot in the North Island city of Hamilton, said demand for avocado trees had increased "hugely" in recent years as the fruit became more popular in everyday cooking. Avocado toast has become a hit among young, health-conscious adults in New Zealand as well as in other countries.

With trees arriving only in two or three shipments a year, Mr Grilli said, up to half are typically sold in pre-orders before stock is delivered, with the rest snapped up soon after. The store did not currently have any avocado trees in stock and was awaiting another shipment, he said.

Those eager to secure their own avocado toast supply will need patience, Mr Grilli said.

"All going well, from planting the tree, in four or five years, you're going to be getting into some pretty good fruit."