Detection and Pathogenic Impact Assessment of Fusarium Spp. On Horseradish in Vojvodina (Serbia)

Horseradish grows well in Serbia on fertile, well-drained soils, tolerates cold winter conditions, and produces high-quality roots when appropriate agronomic practices are applied, particularly with planting and harvesting carried out in late autumn. Among the horseradish diseases, pathogens causing root diseases pose a major challenge by adversely affecting product quality, marketability, and grower revenue. In 2025, internal discoloration of horseradish roots was observed in an open-field production area in the Manđelos region (Vojvodina, Serbia). The disorder was characterized by dark brown to black discoloration of the vascular tissue, which progressively spread both inward toward the central core and outward toward the cortical tissue of the roots. Symptomatic samples after sterilization, were used for inoculation procedures on nutritive media (PDA) Small parts were taken from the tissue that were between the healthy and the diseased area, then they were cut into equal parts and placed on the PDA medium. After seven days, colonies showed white aerial mycelia with purple to violet pigmentation, while one isolate was pale white to cream. Morphological differences suggest two Fusarium species. Microscopy revealed numerous hyaline, mostly single-celled, oval to ellipsoidal microconidia. All tested isolates (H1, H2, and H3) induced similar symptoms on healthy horseradish roots, with no notable differences in disease progression or symptom severity, suggesting comparable aggressiveness among isolates. Successful reisolation of the pathogens and confirmation of identical morphological characteristics fulfilled Koch’s postulates and confirmed the causal role of Fusarium spp. in horseradish root rot. Further research will include the application of molecular methods to enable precise identification of the pathogen at the species level.