ISHS Acta Horticulturae 695: I International Symposium on Tomato Diseases
RALSTONIA SOLANACEARUM DETECTION IN TOMATO IRRIGATION PONDS AND WEEDS |
| Authors: | J. Hong, P. Ji, M.T. Momol, J.B. Jones, S.M. Olson, P. Pradhanang, K. Guven |
| Keywords: | Polygonum pensylvanicum, Hydrocotyle ranunculoides, bacterial wilt, alternative host, aquatic weed, irrigation water, population dynamics, pulse field gel electrophoresis |
| DOI: | 10.17660/ActaHortic.2005.695.36 |
| Abstract:
Bacterial wilt caused by Ralstonia solanacearum is an important disease in tomato production in Florida. Populations of R. solanacearum were monitored in irrigation pond water in Northern Florida over the past three years to determine the pathogen’s source of inoculum and the cycle of the population. Water samples from different irrigation ponds were taken in monthly intervals and were plated on semi-selective medium SMSA. Presumptive colonies of R. solanacearum were confirmed by whole-cell fatty acid methyl esters analysis and/or ELISA. The pathogen population appeared to be temperature-dependent, increasing in the summer and decreasing in the winter. Populations peaked in the summer months reaching up to 1.5 x 104 colony-forming units per ml, yet undetectable in the winter and early spring. Inoculation of tomato plants using collected summer pond water resulted in bacterial wilt under greenhouse conditions. Aquatic weeds in or surrounding the irrigation ponds were assessed to determine their role as alternative hosts or sources of the pathogen. Several dominant weeds in the area, including Polygonum pensylvanicum and Hydrocotyle ranunculoides, harbored the pathogen. Genomic DNA from representative R. solanacearum strains isolated from the irrigation ponds and aquatic weeds was analyzed by restriction digestion with Xba I, or Dra I followed by pulsed field gel electrophoresis (PFGE). These results indicated that R. solanacearum infested irrigation ponds and aquatic weeds could be a significant source of inoculum for bacterial wilt. | |
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