Isolation of T-2 toxin-producing fungi from forage corn grown in northern Japan

In this study, we investigated the occurrence of T-2 toxin-producing fungi in domestically grown corn forage. We isolated fungi, using a Fusarium-selective medium, from corn forage samples collected from eight farms or agricultural organizations in Iwate (2018) and Hokkaido (2020) prefectures. The isolated fungi were cultured on corn grits to assess T-2 toxin production. We identified 16 T-2- toxin-producing strains, among which, strains seven and nine were isolated from Hokkaido and Iwate samples, respectively. Toxin-producing fungi were isolated from grains, stem leaves, silks, and bracts. Of the four strains isolated from the grains, one was isolated from a sample exhibiting grain disease symptoms, whereas the remaining strains were isolated from grains showing no obvious disease symptoms. In Iwate samples, four and five fungal strains were identified as Fusarium sporotrichioides and Fusarium armeniacum, respectively, whereas all seven strains isolated from Hokkaido corn samples were identified as F. sporotrichioides. Although T-2 toxin has rarely been detected or detected at low concentrations in domestic feeds, our findings revealed that T-2 toxin may constitute a new threat to forage production in Japan.