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Poster: Diseases of Plants: New & Emerging Diseases


Laurel wilt, caused by Raffaelea lauricola, is detected for the first time outside the southeastern USA
R. PLOETZ (1), Y. Thant (2), M. Hughes (3), T. Dreaden (4), J. Konkol (1), A. Kyaw (2), J. Smith (3), C. Harmon (3) (1) University of Florida, U.S.A.; (2) Winrock International, Farmer-to-Farmer Program, Yangon, Myanmar, Burma; (3) University of Florida,

Agriculture is an important industry in Myanmar (aka Burma), accounting for 60% of the GDP and employing 65% of the work force. In October 2014, a survey for diseases and pests of an emerging fruit crop in the country, avocado (Persea americana), was conducted in Southern Shan State. Around Tuanggyi, monocultures of up to 20 hectares have been established, whereas avocado is an over-story tree where coffee is grown in the Ywangan area. Symptoms of laurel wilt, including sapwood discoloration, leaf necrosis, defoliation, and tree mortality were observed during the survey in both areas. In Myanmar, isolates that resembled the laurel wilt causal agent, Raffaelea lauricola, were recovered from symptomatic sapwood on ½ strength potato dextrose agar + streptomycin sulfate. In the USA, R. lauricola-specific amplicons were generated for isolates from eight different trees with PCR primers for two taxon-specific microsatellite loci. In a quarantine greenhouse in Gainesville, FL, three of the isolates caused laurel wilt in each of two tests on avocado and swamp bay (P. palustris), with disease severities similar those caused by an isolate of R. lauricola from the USA. Although R. lauricola was probably introduced from Asia to the southeastern USA with its ambrosia beetle symbiont, Xyleborus glabratus, it had previously been reported only in the southeastern USA. This is the first report of laurel wilt in the Asian homeland of R. lauricola and X. glabratus.