Farmers in the North Island are being warned to remain vigilant as high levels of facial eczema are being recorded in many areas.
The fungus, which produces the toxic spores, thrives on drought desiccated pastures where the surface soil temperatures remain warm following rain.
Asure Quality's facial eczema monitoring co-ordinator Leo Cooney says farmers should be seeking advice from their vet.
"And certainly carry on with precautions until these spore counts and soil temperatures start coming down. It will depend entirely on the weather sometimes we've had facial eczema extending into May in some areas."
Mr Cooney says even though air temperatures are dropping, it takes a while for soil to cool down.
Susceptible animals will be affected by severe liver damage.