Pseudomonas syringae causing bacterial canker on apple trees in Brazil

ABSTRACT

In March 2016, wilt and shoot blight were observed on five-year-old apple trees (Malus domestica) cultivar Maxi Gala in a commercial orchard in São Joaquim city, state of Santa Catarina, Brazil. Isolation on culture media, biolog, biochemical, LOPAT tests, and whole genome sequencing were performed. Koch’s postulates were fulfilled on apple stems, leaves and fruits. The taxonomic position of a representative strain was determined by in silicoDNA-DNA hybridization using the Genome-to-Genome Distance Calculator which showed 93.9% similarity with Pseudomonas syringae. Results of biolog and biochemical tests did not match those expected for pv. papulans, morsprunorum or syringae. To our knowledge this is the first report of P. syringae causing bacterial canker in commercial apple orchards in Brazil.

Key words bacterial canker; bacterial ooze; blister bark; blister spot; blossom blast; internal necrosis