In some places stem rust may become endemic before the outside world even spots it.

ECONOMIST: Wheat rust and world farming

When the good luck runs out, stem rust can destroy the entire harvest in an infected area.

ECONOMIST: Wheat rust and world farming

Scientists such as Mr Coffman say they know how to attack stem rust.

ECONOMIST: Wheat rust and world farming

Wheat Stem Rust is a devastating wind-born disease affecting cereals that has spread across Africa and is now in the Middle East, and migrating further eastwards.

CNN: Feeding the future: Saving agricultural biodiversity

But new research found that, like stem rust, stripe rust increases its genetic variability by reproducing sexually on the leaves of another host plant (the barberry), making itself more adaptable and more deadly.

ECONOMIST: Wheat rust and world farming