Septoria secalis[1] is a common disease that mainly attacks rye leaves.

Small spots appear between leaf veins, elongate, then turn yellow-brown and become pale.

The disease appears most often on seedling leaves during the autumn, but also affects adult plants.

Severe attacks of Septoria secalis can result in crop yield losses between 10% and 40%.

Yan & Hunt 2001 finds that in most years SLB is the primary yield loss factor in Ontario, Canada.