ISHS Acta Horticulturae 695: I International Symposium on Tomato Diseases
TOMATO PITH NECROSIS (TPN) CAUSED BY P. CORRUGATA AND P. MEDITERRANEA: SEVERITY OF DAMAGES AND CROP LOSS ASSESSMENT |
| Authors: | M.L. Moura, M.A. Jacques, L.M. Brito, I.M. Mourão, J. Duclos |
| Keywords: | Lycopersicon esculentum Mill., Pseudomonas corrugata, Pseudomonas mediterranea, pith necrosis, disease severity |
| Abstract:
Tomato pith necrosis (TPN) is caused mainly by soil-borne Pseudomonas spp., formerly known as Pseudomonas corrugata (Roberts and Scarlett, 1981). Considerable phenotypic diversity and evidence of genomic variability were the basis of the characterisation of two species within this group: P. corrugata and P. mediterranea sp. nov. Both have been isolated in several countries, including Portugal. There is no report on the relative aggressiveness of these two TPN-causing Pseudomonas species under commercial-like greenhouse conditions. In this study, severity and progress of pith necrosis caused by P. corrugata and P. mediterranea were compared under spring/summer greenhouse conditions in northern Portugal. In addition, a precise assessment of the yield of tomatoes (number, size and weight of fruits) was carried out to determine the relationship among bacterial species, disease severity and yield loss. Tomato plants were stem injected with either strain A344 of P. corrugata or strain A54 of P. mediterranea, 45 and 60 days after transplantation in the greenhouse. TPN symptoms were recorded throughout the growing period. Yield of tomato fruits was assessed weekly during the last seven weeks. Both strains showed a similar level of aggressiveness and caused the same type of symptoms. Both strains were responsible for significant yield reductions, however, no correlation (p≥0.05) was found between pith lesion length and fruit loss. | |
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