Abstract

MARTINEZ, Valeria et al. Studies of survival and dispersal of Xanthomonas citri subsp. citri on lemon fruit. Rev. ind. agric. Tucumán [online]. 2014, vol.91, n.2, pp.17-24. ISSN 1851-3018.

Experiments were conducted in Tucumán, Argentina, to study Xanthomonas citri subsp citri potential for survival in lemon fruit (Citrus limon (L.) Burm. f.) after conventional packing and storage treatments. In order to conduct these studies, canker free fruit was picked from infected plots, processed in the packing line and stored at 6°C. Samples were taken periodically and bacteria populations present on the fruit surface were evaluated in a selective medium (nutrient agar) and biological testing on Duncan grapefruit leaves. These trials were conducted at three different moments of the export seasons 2006 and 2007: at the beginning in April, in June, and finally in August. The results showed that commercial packing treatment eliminated bacteria population from the surface of asymptomatic fruit. Harvesting date was an important factor, as it determined the initial amount of bacteria naturally present on the epidermis of the fruit. Conventional post harvest treatments and a 6°C storage temperature are effective measures for fruit inocuity and provide phytosanitary guarantees for international trade. Natural dispersal of the disease from fruits severely infected with citrus canker as inoculum source was also studied, by placing discarded canker-infected fruit in cull piles near highly susceptible Duncan grapefruit (Citrus paradisi, Macf.) seedlings. These plants were observed for 14 months, and in no case was canker detected on the leaves. This study was conducted as part of an international project, with a unique protocol previously agreed.

Keywords : citrus canker; innocuity; packinghouse treatments; bacterial survival; disease spread.

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