Septoria under the radar

Septoria disease caused by Septoria linicola is a fungal disease of flax that is mainly observed in France. The disease is mainly observed on winter flax, however with the multiplication of flax cultivated areas in the Interreg region, the disease is also making its way to Belgium. In case of high disease pressure, a yield loss can reach up to 70%.

The first symptoms can be recognized by circular brown spot on the basal leaves, which spread from the bottom to the top of plants. Then some characteristics symptoms with alternating yellow-brown stripes can be observed on the stem, followed by an early senescence of plants. The disease occurs mainly in wet and humid weather. Whereas in 2025 little to no symptoms have been observed due to the drought, this year the disease was slightly more present. The wetter month of February may have played a role in this. As part of the Trans-Pathoflax 2.0 project, an information sheet was produced presenting symptoms, conditions and possible control measures.

Take a look at the fact sheet below and learn about this emerging plant disease!