Field library

Yellow Rust

Yellow-orange powdery stripes run in neat lines along the leaf veins. Rubbing a leaf leaves yellow dust on your fingers. It builds fastest in cool, damp weather between 10 and 15°C, especially where morning dew sits on the crop, and can strip a field of grain filling within two to three weeks if it is left alone. Late-sown and heavily fertilised wheat suffers worst.

How to scout

Walk into the field, not just along the edge. Check the lower and middle leaves of 20 plants at five spots. The first spots usually appear in a patch rather than across the whole field, so look for a circle of yellowing plants.