Symptoms

Symptoms are the same as other wheat stem rust pathotypes. The symptoms start as oblong blisters on the stems and leaves, developing lengthwise along the plant. These blisters break open after a couple of days to reveal a mass of rust coloured spores.

If stem rust is detected on a wheat line which is thought to be resistant, samples should be sent for testing. Contact details for Australian RustCereal Survey can be found in the resources section.

Organism

Puccinia graminis f. sp. tritici, pathotype Ug99

Host range

Wheat and other cereal crops.

Method of spread

Wind, contaminated clothing, machinery and tools.

Conditions favouring disease

Generally, for Puccinia graminis, the most important requirement for disease is susceptible varieties of wheat. Thereafter, warm (15 to 30°C) and humid conditions are needed together with abundant spring rain. Also, favouring disease is an accumulation of spores from infected and self-sown wheat plants growing before the main crops are planted.

Confused with?

Other stem rusts of wheat. Expert diagnosis is required if a resistant cultivar is being cultivated and develops stem rust. Early detection is important in controlling this pathogen.

Where?

A number of stem rust pathotypes are present in Australia and resistant varieties of wheat have been bred to limit crop losses. This new pathotype was discovered in Uganda in 1999, and is now found in Kenya, Ethiopia, Sudan, Yemen and Iran.