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Factors Affecting the Activity of a Volatile Fungistatic Substance in Certain Alkaline Soils. W. H. Ko, Associate Professor, Department of Plant Pathology, University of Hawaii, Beaumont Agricultural Research Center, Hilo 96720; F. K. Hora, Technician, Department of Plant Pathology, University of Hawaii, Beaumont Agricultural Research Center, Hilo 96720. Phytopathology 64:1042-1043. DOI: 10.1094/Phyto-64-1042.

Hydrogen peroxide treatment of an alkaline soil decreased the organic matter content 90%, while more than 70% of the volatile fungistatic substance was retained. The volatile inhibitor existed in the fractions of sand, silt and clay, and did not completely disappear from soil after ignition at 400 C for 12 h. The amount of the volatile inhibitor released was directly correlated with the amount of water added. No volatile inhibitor was released from soil with the same moisture content as that under field conditions. Results suggest that the volatile inhibitor from certain alkaline soils is inorganic in nature, and that it is released under natural conditions only when the soil is wet, a situation which is not common in the regions where alkaline soils occur.