Authorities inspecting maple syrup farms in Quebec, Canada, have found almost half of farmers using a banned chemical on their trees. Paraformaldehyde, which is used for keeping the holes drilled in trees from closing up. It has been illegal in Canada since 1991 but the country's Pest Management Regulatory Agency has shown that is still being widely used, illicitly, in Quebec. Producers caught using the substance may be fined up to C$50,000 (US$32,500) and face criminal charges.

By Monica Dobie, just-food.com correspondent in Montreal, Canada