Dispersal of banana blood disease in Southeast Asia
Jane Ray: The University of Queensland
<div>Blood disease of banana caused by <em>Ralstonia syzygii</em> subsp. <em>celebesensis</em> falls within phylotype IV of the <em>Ralstonia solanacearum</em> species complex. Symptoms include characteristic vascular staining, fruit bunches which appear outwardly healthy but are internally stained red/brown and rotten. Dispersal is associated with infected suckers, soil, tools and by insects. The disease was first observed in 1905 on Pulau Selayar a small island to the south of Sulawesi in Indonesia. It soon spread to the island of Sulawesi where a quarantine order in 1921 contained the disease. In 1987 the disease was detected in West Java from here it spread relatively quickly and was recorded in Bali and Sumatra (1994), Lombok, Sumbawa and West Papua (1999) and peninsular Malaysia (2013). We sought to determine the recent distribution through surveys. In Sumba, samples were collected from the symptomatic banana cultivars Pisang kepok (cooking ABB), Pisang ambon (sweet AAA) and Pisang barangan (sweet AAA). Bacteria were isolated from the samples and subsequently confirmed as <em>Ralstonia syzygii</em> subsp. <em>celebesensis</em> using molecular techniques. Initial analysis reveals a rapid spread from infested areas of ~75km/year. The severity of banana blood disease is significant as on Sumba the popular but highly susceptible Pisang kepok is no longer grown for export to other areas of Indonesia and subsistence farmers reported losses of 75-100%.</div>
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