Also known as Black rust
Puccinia graminis Pers.:Pers.

1. Symptoms: Pustules (containing masses of urediospores) are dark reddish brown, and may occur on both sides of the leaves, on the stems, and on the spikes (see picture). With light infections the pustules are usually separate and scattered, but with heavy infections they may coalesce. Prior to pustule formation, "flecks" may appear. Before the spore masses break through the epidermis, the infection sites feel rough to the touch; as the spore masses break through, the surface tissues take on a ragged and torn appearance.
2. Development: Primary infections are usually light and develop from wind-borne urediospores that may have traveled long distances. The disease can develop rapidly when free moisture (rain or dew) and moderate temperatures prevail. If temperatures average about 20°C or more, the first generation of urediospores will be produced in 10-15 days. As plants mature, masses of black teliospores may be produced.
3. Hosts/Distribution: Stem rust can affect wheat, barley, triticale, and many other related grasses; it is found wherever temperate cereals are grown. The alternate hosts are Berberis and Mahonia spp.
4. Scoring tables

References and further reading:

• Rust Diseases of Wheat: Concepts and methods of disease management
• Rust Scoring Guide

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