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Effect of Water Potential on the Growth and Survival of Macrophomina phaseolina. F. M. Shokes, Former Graduate Research Student, Department of Plant Sciences, Texas A & M University, College Station, TX 77843, Present address of senior author: Department of Plant Pathology and Plant Genetics, University of Georgia, Athens, GA 30602; S. D. Lyda(2), and W. R. Jordan(3). (2)Associate Professor, Department of Plant Sciences, Texas A & M University, College Station, TX 77843; (3)Associate Professor, Blacklands Conservation Research Center, Temple, TX 76501. Phytopathology 67:239-241. Accepted for publication 1 September 1976. Copyright 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-239.

A vapor-equilibration technique was developed to study the effect of growth-medium water potential on growth of Macrophomina phaseolina. Maximum growth at 30 C was attained at water potentials near 17 bars, with reduced growth above and below this water potential. Some growth was observed after 50 hr on media having water potentials as low as 38 bars. Recovery of viable sclerotia from Edna fine sandy loam soil indicated that incubation for 2 wk at soil water potentials between 0.01 and 11.8 bars is deleterious to sclerotia survival only in soils maintained near saturation. The number of viable sclerotia recovered from saturated soils was reduced an average of 35%.