Update on the maize ear rot caused by Trichoderma afroharzianum in Europe
Trichoderma afroharzianum has been added to the EPPO Alert List because of concerns that it was associated with severe ear rot symptoms in maize (Zea mays) but its pathogenicity has been contested (EPPO RS 2022/087, RS 2023/194, RS 2024/140).
In 2018-2024, Trichoderma spp. strains were isolated from 54 sampling sites from maize cobs and agricultural soil in various locations across Europe (mainly Germany but also Austria, France, Italy, Türkiye). Trichoderma ear rot disease was first identified in Austria in Neustift, Heiligenkreuz, and Rudersdorf (Nordburgenland region, near the borders with Slovakia and Hungary). Pathogenic T. afroharzianum isolates were also recovered for the first time from Türkiye: in Salihli (Manisa province, Aegean region) and Tarsus (Mersin province, Mediterranean region). In France, T. afroharzianum isolates were recovered from new regions: Aquitaine and Bourgogne.
T. afroharzianum was the only species exhibiting high pathogenicity on maize cobs. Other Trichoderma species, such as T. harzianum colonized maize cobs endophytically without causing symptoms.
The study showed that T. afroharzianum is prevalent in warmer and drier regions of Europe, and absent in cooler, wetter northern regions. This suggests that temperature and precipitation are key factors influencing the occurrence of pathogenic Trichoderma species.
Sources
Pfordt A, Douanla-Meli C, Voll F, Schrader G, Schäfer BC, von Tiedemann A (2026) Effect of temperature and precipitation on the occurrence of Trichoderma ear rot in Europe. Phytopathology Research 8(1), 11. https://doi.org/10.1186/s42483-025-00396-4
Pfordt A, Von Tiedemann A (2025) Commentary: Is Trichoderma ear rot on maize really a new dangerous plant disease? Frontiers in Agronomy 7, 1544363. https://doi.org/10.3389/fagro.2025.1544363
Pfordt A, Steffen L, Raz T, Naumann M (2024) Impact of Trichoderma afroharzianum infection on fresh matter content and grain quality in maize. Frontiers in plant science 15, 1436201. https://doi.org/10.3389/fpls.2024.1436201