Stripe Rust of Wheat

• Stripe rust, also called yellow rust, is caused by the fungal pathogen Puccinia striiformis.
• This disease can be distinguished from stem and leaf rust by the formation of the pustules and the coloration of the urediniospores.
• This pathogen is common in areas with higher elevations due to the cooler climate with frequent leaf wetness.

• Initial symptoms are circular to oval yellow spots on upper leaf surfaces at the infection sites.
• These develop into yellow-orange pustules bearing urediniospores that dust off when disturbed.
• Lesions elongate, forming a notable stripe shape on leaf surfaces.
• Photosynthesis is reduced as functional leaf area decreases, which can reduce head fill and yield.
• Darker colored teliospores form later in the season.

Urediniospores from Puccinia striiformis.

• Stripe rust can develop at lower temperatures than other rust diseases. Development is favored by 50-64° F (0-18° C) temperatures with at least six hours of dew present.
• Stripe rust can survive winter temperatures above 23° F (-5° C).
• Urediniospores can travel long distances, spreading from field to field via wind.

• Planting resistant wheat varieties is the primary method to reduce losses to stripe rust.
• There are two types of genetic resistance to stripe rust: seedling resistance and adult plant resistance.
  • Seedling resistance is effective throughout the life of the plant, but is usually only against some races of the pathogen.
  • Adult plant resistance develops as plants mature.
• If growing a susceptible variety, and infection occurs on the flag leaf, then foliar fungicide application may be justified.
• Decreasing irrigation in fields also limits the amount of water available for leaf wetness, disfavoring disease development.

• CAHNRS & WSU Extension. (n.d.). Wheat & Small Grains. Retrieved from Washington State University College of Agriculture, Human, and Natural Resource Sciences.
• Martinez, A., Youmans, J., & Buck, J. 2009. Stripe Rust (Yellow Rust) of Wheat. Retrieved from University of Georgia Extension.