Grain farmers are being warned that a locally-bred wheat variety is showing signs of being less resistant to the fungal disease, leaf rust.
The Conquest Milling Wheat was bred four years ago by Plant and Food Research and had proven to be disease resistance, but some crops in mid-Canterbury are showing signs of leaf rust.
The Foundation for Arable Research project manager Rob Craigie says either the leaf rust has mutated, or the outbreak has been caused by this season's environmental conditions.
Mr Craigie says it is disappointing the cultivar has lost its resistance, but it not uncommon for this to happen.
He suggests farmers monitor crops and apply fungicide if needed.