Dropping consumer demand for kūmara means growers are set to face big losses this year.

Kaipara Kūmara grows the vegetable in Ruawai in Northland and produces about 6000 tonnes a year.

Managing director Anthony Blundell says sales of kūmara were down by about 10 to 15 per cent and he was unsure why.

"It's something I often want to go and ask shoppers.

"There's a little bit of an oversupply, but not to a great extent when you compare it to other years.

"For whatever reason, kūmara is not being picked up as regularly as they used to be.

"Maybe the fact that we're in this inflationary environment people are watching what they spend, but kūmara is really competitively priced at the moment around three dollars a kilo so I don't know what's going on."

Blundell says growers are dealing with increased costs of labour, fertiliser and compliance costs, so a drop in demand and subsequent lower prices were hampering grower's returns.

"Returns on average are significantly below the cost of production.

"Hopefully we're in a little bit of a trough and things pick up again next year, but it's a bit of a slog for growers this year."

Growers will probably plant less kūmara for next season to try to reduce losses, he says.

"All we can hope for is that with the prices being low at the moment more people get out and buy kūmara to support the growers."

-Sally Murphy/RNZ.