Septoria Complex, Speckled Leaf Blotch, Glume Blotch Septoria Complex, Speckled Leaf Blotch, Glume Blotch Leptosphaeria avenaria f. sp. This group of diseases is known as Septoria complex because they all may be present in the same field and even on the same plant. The Septoria complex of diseases occurs mainly on wheat, but is common on barley, oats, rye and grasses, especially Poa and Agrostis spp. They are widespread throughout the Prairie Provinces.
Spores infect the new crop during wet weather.
Secondary infection to nearby plants results from spores produced on infected leaf spots transported by splashing rain and wind. Wet windy weather favours this disease, while dry conditions reduce or prevent new infections and spore production on diseased plants. Plants must remain wet for six hours or more for successful spore infection. Increases in the incidence of this disease are related to denser, more humid foliage that occurs with higher nitrogen inputs. The disease develops on all above-ground plant parts.