Friday, 23 August 2013 15:18
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PAINTER, VA—Many commercial vegetable growers on Virginia's eastern shore depend on the production of healthy tomato crops for their livelihoods; almost 4500 acres of fresh tomatoes are grown annually in the region. But a deadly bacterial wilt is devastating tomato crops on the Eastern Shore and throughout the southeastern United States. According to the authors of a new study, yield reductions of up to 50% have been observed in some fields throughout the region.

"The practice of rotating tomato crops with non-susceptible crops has been the most effective way to control bacterial wilt caused by Ralstonia solanacearum, but Eastern Shore tomato producers do not have the available farmland to rotate tomato crops for extended periods of time while maintaining profitability," said Steven Rideout, the lead author of the research study. Rideout and colleagues Adam Wimer and Joshua Freeman, research scientists from the Eastern Shore Agricultural Research and Extension Center at Virginia Polytechnic Institute and State University, published the results of their multi-year study of tomato wilt disease in HortTechnology.

The team evaluated four commercial tomato fields and documented the distribution of bacterial wilt in fields naturally infested with Ralstonia solanacearum. They assessed the tomato plants throughout the growing seasons and recorded the incidence of bacterial wilt for individual plants. "Our results indicated that disease pressure increased throughout the growing season," Rideout said. "We determined that tomato bacterial wilt became more clustered within rows as the growing season progressed. We found positive correlations between disease incidence and the percentage of rows exhibiting a significantly clustered distribution in every trial."

Study results also indicated that a common factor (or factors) contributes to a clustered distribution within rows. "Analysis of the data across rows using ordinary runs did not show a high percentage of clustering, indicating spread within rows is more important than across rows in the development of bacterial wilt epidemics," the report said.

To help commercial tomato growers attack the deadly disease, the researchers recommend reducing the frequency of irrigation as a possible alternative to currently used irrigation regimes. "Growers on Virginia's Eastern Shore commonly irrigate twice daily; reducing the frequency of irrigation could create dry periods within the beds that may reduce disease incidence or slow the spread of the pathogen within a field," they said.

The study suggested the need for additional research to examine if increased plant spacing, limiting the root-to-root contact of neighboring plants, or possible irrigation alternatives could suppress the disease without reducing yields.

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The complete study and abstract are available on the ASHS HortTechnology electronic journal web site: http://horttech.ashspublications.org/cgi/content/abstract/21/2/198

Founded in 1903, the American Society for Horticultural Science (ASHS) is the largest organization dedicated to advancing all facets of horticultural research, education, and application. More information at ashs.org


 

Original Article:

Temporal and Spatial Distribution of Tomato Bacterial Wilt on Virginia's Eastern Shore
Adam F. Wimer, Steven L. Rideout, and Joshua H. Freeman
HortTechnology 21:198–201. [Abstract][Full Text][PDF]

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