Authors
Deanna L. Funnell-Harris, Grain, Forage, and Bioenergy Research Unit (GFBRU), United States Department of Agriculture–Agricultural Research Service (USDA-ARS), and Department of Plant Pathology, University of Nebraska, Lincoln 68583-0937; and
Jeffrey F. Pedersen, GFBRU USDA-ARS and Department of Agronomy and Horticulture, University of Nebraska, Lincoln
Abstract
Sorghum grain, valuable for feed, food, and bioenergy, can be colonized by several Fusarium spp.; therefore, it was of interest to identify possible sources of conidia. Analysis of air and soil samples provided evidence for the presence of propagules from Fusarium genotypes that may cause grain infections. Soil population estimates of members of the Gibberella fujikuroi species complex, that includes sorghum pathogens and other Fusarium spp., suggested that adequate inoculum for systemic infections was present. Conidia in air samples within two sorghum fields were collected by passive trapping for 2 years. Subsampled Fusarium isolates indicated that numbers of G. fujikuroi increased from anthesis through maturity, which coincides with grain development stages vulnerable to Fusarium spp. Genotyping using translation elongation factor 1-α gene sequences revealed that spore trap isolates included members of G. fujikuroi that are sorghum pathogens: Fusarium thapsinum, F. verticillioides, F. proliferatum, and F. andiyazi. Also detected were F. graminearum, F. subglutinans, and several F. incarnatum-F. equiseti species complex haplotypes that colonize sorghum asymptomatically. All commonly found grain colonizers were detected from air samples in this study.
