To make sure his scales weren't out of kilter, the resident of Pt England in Auckland's eastern suburbs took the puny bag of spuds back to the Crack A Jack Dairy where he bought them. He said the Glen Innes dairy staff agreed on the spot the spuds were underweight and refunded him.
"They're not to blame, it's the supplier to blame," Rowlands said.
However, the dairy refused to tell Rowlands or the Herald on Sunday who supplied the measly bag, saying only it had a range of suppliers.
The newspaper weighed six bags from the dairy. Four were between 9.7kg and 10kg. One was 10.3kg. Another weighed only 8.9kg - not much more than the bag Rowlands picked up. The underweight bag was a generic black "Quality Potatoes" bag similar to the one purchased by Rowlands.
The only contact details on the bags are for bag manufacturer Mark Freeman, who does not pack the potatoes.
Freeman said he's been caught in the crossfire whenever irate customers found rotten, wormy or underweight potatoes. Freeman had 30 years' experience in the industry and his advice to consumers was to always check bags for the name of a grower name or supplier. "A bona fide grower will always put his name on the bag."
Trustworthy bags also usually have stickers with packing dates to give people an indication of potato freshness.
Freeman said he supplied the bags to Hortigro who sold them to merchants who bought potatoes from growers around Pukekohe.
"There's probably at least a dozen guys that float around Pukekohe buying potatoes. These roosters that are running around buying from growers ... I imagine they go back to their garage and bag them up."
Thankfully, Freeman said traders who short-changed consumers were a minority.
"I would say nine times out of 10 the weights will be correct, because they're done with an automated bagger." Automated weights were normally set at 10.8kg, to compensate for any moisture loss as the potatoes aged.
Rowlands said he has complained to the Commerce Commission. He said he is now very suspicious of any generic-bagged potatoes.
It is illegal under the Fair Trading Act to mislead customers. Any trader who knowingly sells produce well under the weight stated on the packaging can be charged under the act. And it's an offence under the Weights and Measures Act if the weight, measure, or number of goods in a package are less than that stated on the package.
