Wheat Fungal Leaf Disease Identification Roundup

Fungal leaf diseases can be major yield robbers in wheat crops across Manitoba. Leaf diseases reduce plant health and photosynthetic activity, mine plant nutrients and negatively impact grain yield and quality. In Manitoba, there are several yield-restricting leaf diseases, including leaf, stem and stripe rust; the septoria leaf blotch complex; and tan spot. These diseases can be found across all of Agro-Manitoba.  Below is information on identifying features and symptoms of each disease.

Leaf rust (Puccinia triticina)

1. Leaf rust does not overwinter in Manitoba. Leaf rust spores are blown into Manitoba from the Southern United States via prevailing winds (Texas-Oklahoma and Kansas-Nebraska corridors). More information on risk of cereal rust movement can be found
2. Leaf rust infections are quite noticeable and are typically confined to the leaf area or the leaf sheath. It consists of small round pustules, that are orange/red in colour. When the plant ripens, the pustules’ colour changes from an orange/red to a dark brown/black due to teliospore development.
3. Leaf rust pustules are scattered throughout the leaf and can cause complete destruction of the leaf tissue.
4. Leaf rust thrives at a wide range of temperatures, ranging between 18-25 °C and moist conditions, including a dew period of at least 3 hours to initiate an infection.