First report of Erysiphe fallax causing powdery mildew on phasey bean (Macroptilium lathyroides) in the United States.
Phasey bean (Macroptilium lathyroides) is a member of the family Fabaceae and is native to tropical America. During the fall of 2017, the leaves of phasey bean plants in Homestead, FL, showed white powdery fungal growth. The morphological characteristics suggested that the pathogen was powdery mildew. For further identification, genomic DNA was extracted from conidia. BLAST results showed that the sequence of FL-1 shares 99% identity to an Erysiphe fallax. Phylogenetic analysis confirmed the closest proximity of FL-1 isolate to E. fallax. Koch's postulates were performed to confirm the pathogenicity.