New azoxystrobin clay carrier to control corn late wilt disease

Corn late wilt disease (LWD), caused by the fungus Magnaporthiopsis maydis, poses a significant threat to corn production in highly impacted regions. Its increasing global relevance is exacerbated by climate change, which facilitates the pathogen’s spread and prevalence. This research supports efforts to broaden LWD management beyond resistant varieties, whose effectiveness can fail within years under high disease pressure. In this study, a novel approach involving the slow release of azoxystrobin from clay carriers was assessed. Two growth-room experiments demonstrated that at the disease’s latent stage (up to 20 days), seed treatment with a clay-azoxystrobin (clay-AS) formulation had minimal impact on early growth indices. However, by day 40, the sepiolite-based treatment increased plant shoot weight by 61%, although pathogen infection levels, monitored via qPCR, remained elevated. A subsequent full-season potted trial revealed significant benefits from applying sepiolite-AS and bentonite-AS formulations directly to the seedbed. At 42 days post-planting, these treatments markedly enhanced plant survival (191% for sepiolite-AS and 64% for bentonite-AS) and improved phenological development (175% and 67%, respectively) compared to unprotected controls, alongside a notable 95% reduction in root infection. By harvest (78 days), bentonite-AS emerged as particularly effective, increasing shoot biomass by 128% and ear yield by 135%. Bentonite-AS treatment reduced cob and shoot symptoms by 23% and 42%, respectively, and nearly eradicated pathogen levels. This research demonstrates that clay-based fungicide formulations effectively mitigate LWD impacts. The method reduces fungicide use and offers a potentially scalable alternative, is adaptable across diverse agricultural systems, and shows potential applicability in managing other soil-borne diseases.