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Influence of Antagonists and Controlled Matric Potential on the Survival of Pseudomonas solanacearum in Four North Carolina Soils. W. C. Nesmith, Extension specialist, Department of Plant Pathology, University of Kentucky, Lexington 40546; S. F. Jenkins, Jr., professor, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616. Phytopathology 75:1182-1187. Accepted for publication 22 May 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/Phyto-75-1182.

Large numbers of microorganisms antagonistic to Pseudomonas solanacearum were detected in each of two suppressive soils (Worsham and Arapahoe) and two conducive soils (Norfolk and Torhaunta). In the suppressive soils, highest populations of antagonistic bacteria were detected in Worsham soil and the highest populations of antagonistic fungi and actinomycetes were in the Arapahoe soil. Lowest populations of antagonists were associated with the Norfolk soil. Soil moisture significantly affected reproduction and survival of P. solanacearum in unsterile soils, regardless of soil type; colony counts increased within 7- 10 days of introduction into the soil at the highest soil moistures (from flooded to - 1 bar), but did not increase in drier soils (from - 5 to - 15 bars). The most favorable soil moisture for survival of P. solanacearum was - 0.5 to - 1 bars. Decline of P. solanacearum was more rapid when added to the four soils 60 days after imposing moisture regimes than when added on day 1. Soil type, which influenced soil moisture, determined the size of antagonistic populations, which in turn affected the survival of P. solanacearum in soil.

Additional keywords: biological control, soilborne pathogens.