It is a wheat plant pathogen causing septoria leaf blotch that is difficult to control due to resistance to multiple fungicides.

Sometimes in culture nonseptate, hyaline microspores, measuring 1-1.3 × 5-9 μm, occur outside pycnidia by yeastlike budding.

[12] Sexual state (teleomorph): Pseudothecia are subepidermal, globose, dark brown, and 68-114 μm in diameter.

[12] Zymoseptoria tritici represents an intriguing model for fundamental genetic studies of plant-pathogenic fungi.

[11] Dispensable chromosomes have originated by ancient horizontal transfer from an unknown donor, that was followed by extensive genetic recombination, a possible mechanism of stealth pathogenicity and exciting new aspects of genome structure.

[13] Goodwin et al. (2011)[13] suggested, that the stealth pathogenesis of Zymoseptoria tritici probably involves degradation of proteins rather than carbohydrates to evade host defenses during the biotrophic stage of infection and may have evolved from endophytic ancestors.

[13] The fungus Zymoseptoria tritici has been a pathogen of wheat since host domestication 10,000–12,000 years ago in the Fertile Crescent.

[8] Zymoseptoria tritici shows a significantly higher degree of host specificity and virulence in a detached leaf assay.

[8] Zymoseptoria pseudotritici was isolated in Iran from the two grass species Agropyron repens and Dactylis glomerata growing in close proximity to fields planted to bread wheat (Triticum aestivum).

Unlike most other plant pathogens, Zymoseptoria tritici uses a germ tube to enter the host leaf through stomata rather than by direct penetration.

[13] The fungus evades host defenses during the latent phase, followed by a rapid switch to necrotrophy immediately prior to symptom expression 12–20 days after penetration.

[18] Such a switch from biotrophic to necrotrophic growth at the end of a long latent period is an unusual characteristic shared by most fungi in the genus Mycosphaerella.

[13] Very little is known about the cause or mechanism of this lifestyle switch even though Mycosphaerella is one of the largest and most economically important genera of plant-pathogenic fungi.

These asexual spores are dispersed via rain splash and are response for the secondary inoculum of this polycyclic disease cycle.

[citation needed] Zymoseptoria tritici is a difficult fungus to control because populations contain extremely high levels of genetic variability and it has very unusual biology for a pathogen.

There are also cultural management strategies that may be effective, including regular rotation of crops, deep plowing, and late planting.

[23] Zymoseptoria tritici infects wheat crops throughout the world and is also currently a big problem in Iran, Tunisia, and Morocco.

[26] The need for effective management techniques will become even more important as the prevalence of Septoria leaf blotch increases with climate change.