Stemphylium blight (Stemphylium spp.)

Stemphylium blight: biology

Stemphylium blight is a lentil disease caused by the fungal pathogen Stemphylium botryosum. It is both seed and stubble-borne. On seedlings symptoms are usually at low levels. Wet weather promotes sporulation by the pathogen on the lesions as well as spore germination. Spores are wind-blown.

After wet weather, plants may show high levels of infection that cause maturing crops to appear white. As is common in other lentil diseases, infected leaflets fall to the ground, serving as a source of spores for future infections of plants.

The disease is visible on leaflets at all stages of crop development. Lesions are tan colored, often with angular patterns of lighter and darker areas. They differ from other lentil foliar lesions as they are larger and spread across, or along, the entire leaflet.

Stemphylium blight has been reported to be highly destructive on lentils in countries such as Bangladesh, but the potential for damage in western North America has not been studied. The pathogen may develop extensively only on ageing foliage.

Recent research at the University of Saskatchewan indicates the disease may impact more on quality than quantity. Quality impacts can be in the form of seed staining and smaller seeds – particularly when infections occur in the early stages of flowering.