Northland kumara crop stuck in the mud but prices sky high

German backpackers helping the locals are Mark Kindtner (left) and his friend Marcike Przybylleh. Photo/Supplied

A perfect storm of kumara growing conditions could see consumers pay record prices in the shop this year.

Harvesting machines and small teams of workers would usually have the entire crop tucked away by the end of April in the Dargaville and Ruawai districts, where the country's commercial crop is grown.

But waterlogged conditions mean that on a few large farms workers are trudging barefooted through mud to pick up dirt-caked clumps of kumara because mechanical harvesters can't be used.

Many farms had a late start to planting due to the cold, dry spring; then with seedlings finally in the ground in November and early December rather than up to two months earlier. Then, and needing moisture, they were hit with a very dry, hot summer.

Those factors already spelled a low tonnage yield, but leaving the crop in the ground to "fatten up" left it vulnerable to late summer/early autumn rains that then caused flooding and compaction of the light, alluvial soil.

"Then it was 'wait until tomorrow, it'll dry up. Then it was, no, not today'," Aratapu grower Warren Suckling said.

"We'd normally be all finished by the end of April but harvesting dragged over into May, then it went into June."

A handful of farmers with crops still in the ground have had to employ many hands to manually harvest the ploughed-over crop.

"There are literally people barefeet in the mud, going slowly along the rows, doing what they have to do," Mr Suckling said.

He said he knew of one farmer employing up to 100 workers to bring in what could yet amount to only a small crop.

With the district's final yield not yet tallied up, but which could be down 40 per cent on last year's bumper crop, the price is already $8 to $10 a kg in North Island supermarkets and higher in the South Island where transport costs hike it up.

That is the highest price Locky Wilson, Delta Produce general manager, has seen in 19 years in the business.

"Basically, the whole season has been a nightmare. The kumara crop will be down, we think at this stage, about 30 to 40 per cent on last year's, although that was a record high crop," Mr Wilson said.

"If supply is down and demand still strong, the price will go up. 'Growers' cost of harvest will be high but the increased return from the higher-sell price should ease the pain.

"The other issue down the track, and we don't know about this yet, is that as the crop has been in the ground longer and a bit stressed, will the kumara keep well?"

One of four local packhouses, Delta Produce is a 22-farmer, co-operative packhouse, processor and distributor which handles 45 per cent of the district's kumara crop.

Kumara sales earn about $55 million for the district.

Kumara is a root vegetable only grown commercially in New Zealand in the light, alluvial soils alongside the Northern Wairoa River.

The labour intensive crop requires 120 days to grow in temperatures that do not drop low at night.

Early Maori grew several small varieties, with today's kumara evolving from larger South American varieties brought to New Zealand from the 1850s on whaling ships.

Although known as sweet potato and grown in many countries, it cannot be imported to New Zealand so only local crops are sold here.