Résumé
During 2006-2008, mango disease survey training for pest Iist development was supported under the ASEAN Australia Development Co-operation Program (AADCP) Program Stream: Strengthening ASEAN Plant Health Capacity Project (1). The project involved regional training workshops and practical experience in surveying and disease diagnostics in selected ASEAN countries, in partnership with Australian mango pest and disease specialists. The surveying also provided an opportunity for extending collaboration with CIRAD and for strengthening CIRAD-ASEAN links, when specialist expertise in bacterial disease diagnostics was required. Bacterial canker of mango (or bacterial black spot) caused by #Xanthomonas citri pv. Mangiferaeindicae# (2) is a disease of economic importance in tropical and subtropical producing areas. #X. citri pv. Mangiferaeindicae# can cause severe infection in a wide range of mango cultivars and induces raised, angular, black leaf lesions, sometimes with a chlorotic halo. Suspected leaf lesions of bacterial canker were collected from mango nursery stock cv. Yin Kwe at a nursery in Yangon, Myanmar during March 2007. Sub-samples of representative accessions were dispatched by air-courier to 2CIRAD UMR PVBMT, La Réunion, with additional reference material retained in the plant disease herbarium of'PPD. In tests at CIRAD UMR PVBMT2, nonpigmented Xanthomonas-like bacterial colonies were isolated on KC and NCTM3 semiselective agar media (4,7). Amplified fragment length polymorphism analysis was performed on three isolates from Myanmar and additional reference isolates of xanthomonads originating from Anacardiaceae (#X. citri pv. Anacardii#, #X. citri pv. Mangiferaeindicae#, #X. axonopodis pv. Spondiae#, and #X. translucens# strains from pistachio) (2, 4). On the basis of multidimensional scaling (2), the Myanmar isolates were identified as #X. citri pv. Mangiferaeindicae# and were most closely related to group B strains that were isolated from mango in India and Eastern Asia (5). Mango cv. Maison Rouge leaves, inoculated as previously reported (3) with the Myanmar isolates, showed typical symptoms of bacterial canker 1 week after inoculation. One month after inoculation, mean #X. citri pv. Mangiferaeindicae# population sizes ranging from 5 x 106 to 8 x 106 CFU per lesion were recovered from leaf lesions, typical of a compatible interaction (3). #Mangifera indica# L. probably evolved in the area that includes northwestern Myanmar (6) and to our knowledge, this is the first confirmed detection of #X. citri pv. Mangiferaeindicae# from Myanmar. Further surveys and strain collection will be necessary to evaluate its geographic distribution and prevalence in the country (4). The diagnosis and confirmation of bacterial spot on mango from Myanmar (4) has assisted in the development of Myanmar's mango pest list, and enabled Myanmar partners to gain experience in international collaboration in plant disease specimen dispatch and diagnostics. (Résumé d'auteur)