Septoria

This complex of diseases may be present in the same field or on the same plant. Septoria Leaf Blotch only attacks leaves while Stagonospora Leaf and Glume Blotch affects the leaves and the glumes (heads). Severity of this disease caused by these pathogens increases during wet growing season, resulting in shrivelled grain and a depressed yield.

The fungi overwinter on seed or crop residue as well as on the leaves of winter wheat. Spores infect the new crop during wet weather and spread to nearby plants by rain splash and wind. Wet, windy weather with temperatures of 15-27C favours disease outbreaks. Dry weather reduces the chance of disease.  These diseases characteristically move upward from the initial  infection on the lower leaves within the crop canopy to upper leaves and heads.

Scouting

Initial infections caused by Septoria Leaf Blotch  result in yellow flecks appearing on lower leaves, which develop into yellow, grayish white or brown blotches on all above-ground plant parts. On leaves, yellow bordered lesions are restricted by veins and develop longitudinally with parellel sides and blunt ends. Small dark fungal bodies are found within the lesions.

Leaf lesions caused by Stagonospora Leaf Blotch are light with a dark margin. A chlorotic area develops around the lesions, which are less restricted than those of Septoria Leaf Blotch.

In wheat, the blotches on leaves may be similar to those caused by Tan Spot. However, the presence pycnidia (the dark fungal bodies within the lesions) is an important diagnostic feature that aids in distinguishing these diseases.

Control

There are no resistant cultivators. Foliar fungicides are effective.