A disease of A. annua was observed in August 2007 in Kamuganguzi, near Kabale (south-west Uganda). Affected plants initially showed longitudinal water-soaked stem lesions characteristic of a bacterial infection, which turned into necrotic streaks that split open to expose the pith or in stem breaking. Leaves borne on affected parts wilted and died. Bacterial isolation from leaf material was undertaken on yeast extract peptone glucose agar. A shiny yellow convex, mucoid, bacterial colony dominated isolation plates after 48 h of incubation at 27°C. Fatty acid profiling (MIDI system) and sequencing of the Gyrase B gene revealed that the pathogen was most similar to X. hortorum (Midi ID score = 0.735; sequence similarity to X. hortorum type strain NCPPB939 = 96%). Pathogenicity on A. annua was confirmed. This is the first report of a X. hortorum strain pathogenic on Artemisia. A reference culture is held by the UK National Collection of Plant Pathogenic Bacteria, accession no. NCPPB 4435. The GenBank Accession No. for the gyrB sequence is EU815325.
Ssekiwoko, F.; Mulumba, J.W.; Carter, B.A.; Stanford, H.; Parkinson, N.; Kelly, P.; Smith, J.J. Xanthomonas hortorum pathogenic on Artemisia annua newly reported in Uganda. Plant Pathology (2009) 58 (4) 795-795. [DOI: 10.1111/j.1365-3059.2009.02072.x]