Occurrence of Colletotrichum theobromicola Causing Anthracnose in Onion Floral Stalks in Northeastern Brazil

ABSTRACT

Five Colletotrichum isolates associated with anthracnose symptoms on onion floral stalks were collected from a field used for onion seed production. The isolates were identified as C. theobromicola based on morphological characteristics and phylogeny of the partial gene regions GAPDH and APN2/MAT‐IGS. Pathogenicity assays were conducted on onion inflorescences, leaves and bulbs, and all isolates induced anthracnose symptoms on the three plant organs. The inoculated isolates were successfully reisolated from symptomatic tissues, thereby fulfilling Koch's postulates. To our knowledge, this is the first report of C. theobromicola causing anthracnose on onion inflorescences in Brazil and the first report of this species associated with anthracnose of onion in Northeastern Brazil.