Root Rot Caused by Species of Fusarium on Brassica carinata in South Dakota

Brassica carinata is an emerging oilseed crop in the United States, and root diseases caused by Fusarium have the potential to cause yield losses in production. In this study, B. carinata plants were randomly sampled at vegetative and seed development plant stages from South Dakota State University experimental plots. Reddish-brown lesions were observed on roots of sampled plants from which F. acuminatum, F. oxysporum, F. solani, and F. sporotrichioides were recovered. The Fusarium species were identified based on morphology and phylogenetic analyses of the translation elongation factor 1-alpha gene region. Pathogenicity of the four Fusarium species was evaluated on five B. carinata accessions using a modified inoculum layer method in the greenhouse. At 21 days after inoculation, root rot severity caused by Fusarium on the B. carinata accessions was assessed on a rating scale of 0 to 4 and evaluated using relative treatment effects (RTEs). The F. oxysporum isolate caused significant differences in RTE (P = 0.01) among the B. carinata accessions. However, there were no significant differences in RTE among the B. carinata accessions in response to F. acuminatum (P = 0.82), F. solani (P = 0.76), and F. sporotrichioides (P = 0.47) isolates