Assistant Professor Oklahoma State University Stillwater, Oklahoma
Verticillium wilt, caused by Verticillium dahliae, significantly threatens potato production. While soil fumigation using metam sodium is widely used for disease management, its repeated or successive application may result in side effects. This study investigated the effects of repeated metam sodium fumigation and crop rotation with mustard (Brassica juncea) on Verticillium wilt suppression and associated shifts soil microbial communities. A three-year field trial in Presque Isle, Maine, compared once-, twice-, and thrice-fumigated treatments with and without mustard rotation, and microbial diversity using high-throughput sequencing. Results showed that while repeated fumigation reduced disease severity, its effectiveness declined over time. Mustard rotation reduced V. dahliae inoculum and improved soil health indicators. Soil microbial composition shifted, with certain taxa enriched in frequently fumigated soils. Several microbial genera potentially involved in metam sodium degradation were identified, suggesting microbial adaptation. These findings underscore the need for integrated strategies that combine chemical and biological tools to sustainably manage Verticillium wilt and maintain soil health.
