An AgResearch scientist investigating the effectiveness of treatment for facial eczema in livestock is urging North island farmers not to ease up on protection measures.
Dr Chris Morris is part of a team working on a Ministry of Agriculture & Fisheries project to monitor the use of zinc sulphate.
It's the main form of treatment used to safeguard stock against the fungal disease, which becomes an animal health and welfare problem every summer and autumn, as spore levels build up in pasture.
Zinc is commonly added to stock drinking water, or administered in drenches.
Investigations by the team have found that most of the herds they have checked are under-protected, because farmers aren't putting enough zinc sulphate in the drinking water.
Dr Morris says farmers can get zinc levels in stock drinking water checked by sending a sample to a laboratory.
But he says breeding resistance in livestock is proving to be the most effective long-term method of controlling facial eczema.
Spore counts are still high in many parts of the North Island, but not many cases of the disease have been reported in livestock yet.