More than a dozen maple syrup producers stand accused of illegally boosting harvests with a chemical that can kill trees and even people.

Paraformaldehyde has resurfaced in Quebec more than 20 years after it was banned.

The Federation of Quebec Maple Syrup Producers (FPAQ) told QMI Agency that it has sanctioned 15 cheaters over the past three years.

FPAQ said the harvesters sprayed tapholes with paraformaldehyde, which can prevent scarring around the hole, thereby increasing sap production.

However, the chemical can also kill maple trees and is a suspected cancer-causing agent.

Insertion of paraformaldehyde capsules, the old cheating method, was banned in 1991. Some producers have since obtained a paraformaldehyde spray that's just as dangerous and invisible to the naked eye.

FPAQ inspectors have since updated testing methods, analyzing tree samples instead of relying on visual inspections.

Producers are pleased, pointing out that cheaters could jeopardize Canada's entire syrup industry.

"You really have to have no conscience to use (formaldehyde)," said Chantal Ouimet, a sugar shack owner in Havelock, Que.

"Imagine if our major importer, the United States, decided to stop buying our syrup because of a handful of bad apples, like they boycotted our beef during the mad cow crisis."

Offenders are severely punished.

They can have their entire year's production downgraded to industrial syrup, which pays $1 less per pound.

Canada produces 80% of the world's maple syrup.