Pathogen pathogenicity and host resistance are internal factors in deciding plant diseases. Wheat leaf rust is a kind of worldwide disease.

在病害三角关系中，病原物的致病性及寄主的抗病性是决定病害发生与否的内在因素。

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Before 1949, 13 wheat varieties were released but they are susceptble to stem rust, so wheat production here strained by the disease.

建国前虽推广13个抗旱丰产类型品种，但均不抗秆锈病，致使秆锈病严重，威胁小麦生产。

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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