Septoria

Septoria is a genus of ascomycete fungi in the family Mycosphaerellaceae, within the order Pleosporales. The group includes many species that are plant pathogens, causing leaf spots and related diseases on a wide range of crops and ornamental plants. The best known diseases are Septoria tritici blotch of wheat and Septoria nodorum blotch, which can lead to yield losses and reduced grain quality.

Most Septoria species infect leaves and produce asexual spores inside flask-shaped fruiting bodies called pycnidia. Conidia released from these pycnidia are typically spread by rain splash and, to a lesser extent, wind. In temperate regions, the disease is often polycyclic, with new lesions forming throughout the growing season under suitable wet conditions. Some Septoria species also have sexual stages in other genera, such as Mycosphaerella, linking the asexual and sexual portions of their life cycles.

Hosts are diverse, including cereals, tomatoes, citrus, grapes, and various ornamentals. Septoria tritici blotch, for example, is a major disease of wheat in many parts of the world, while Septoria leaf spots can degrade the appearance and health of many crops. Symptoms typically begin as small, olive-b brown spots with yellow halos on leaves, which may coalesce and cause leaf curling or premature senescence if the infection is advanced.

Management relies on an integrated approach. Cultural practices such as crop rotation, removal of crop residues, and sanitation reduce inoculum. Planting resistant or tolerant varieties when available, and applying appropriately timed fungicide programs, help limit disease. Ongoing monitoring is important due to potential fungicide resistance in some populations.