Survey of Fungal Diseases of Switchgrass Seed and Plants

Progress on development of switchgrass as a dedicated biofuels crop has progressed rapidly in the past few years. Production of switchgrass in large monoculture acreages will increase the risk of plant disease, and the need for development of sustainable disease management practices. We have conducted surveys of commercial switchgrass seed from across the United States, and from field plants in Tennessee for fungal pathogens. Infection rates among seed lots ranged from <1 to 87%. Our studies have revealed several seedborne and soilborne fungal pathogens. These include Alternaria alternata, Bipolaris oryzae, B. sorokiniana, B. spicifera, B. victoriae, Curvularia lunata var. aeria, Fusarium acuminatum, F. armeniacum, F. equiseti, F. graminearum, F. tricinctum, Phoma herbicola, Pithomyces chartarum, and Sclerotinia homoeocarpa. Koch’s postulates were completed for these pathogens to confirm pathogenicity on switchgrass. Many of these fungi are known to cause disease and economic losses in related crops, such as corn, oats, rice, sorghum, wheat, and turf grass. Although these fungi vary in their ability to reduce biomass when inoculated onto mature plants, many can cause significant losses in stand count when applied to seed.