VIEW ARTICLE

Disease Control and Pest Management

In Vitro Activity of Sodium Tetrathiocarbonate on Sporulation and Growth of Six Phytophthora Species. M. E. Matheron, Extension plant pathologist, Department of Plant Pathology, University of Arizona, Yuma Agricultural Center, Yuma 85364; J. C. Matejka, Research assistant, Department of Plant Pathology, University of Arizona, Yuma Agricultural Center, Yuma 85364. Phytopathology 78:1234-1237. Accepted for publication 28 March 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/Phyto-78-1234.

Sodium tetrathiocarbonate releases carbon disulfide when added to water and applied to soils. In vitro tests were initiated to examine growth and sporulation of Phytophthora parasitica, P. citrophthora, P. capsici, P. cactorum, P. cambivora, and P. drechsleri in the presence of sodium tetrathiocarbonate. The duration of zoospore motility for these species was reduced 94% in an aqueous solution containing 12 μg/ml of this chemical. Production of zoospore cysts was reduced 47, 74, and 83% by sodium tetrathiocarbonate at rates of 2.4, 12, and 60 μg/ml, respectively. Zoospore cysts formed in the presence of the compound at 2.4 μg/ml were viable, whereas those formed at 12 μg/ml did not germinate. Sporangium production in soil by P. parasitica, P. citrophthora, P. capsici, and P. cactorum was reduced 23, 65, and 98% in the presence of sodium tetrathiocarbonate at 122, 245, and 490 μg/ml, respectively. However, concentrations of 2,450 μg/ml were needed to completely inhibit mycelial growth by all species. These results suggest that application of sodium tetrathiocarbonate as a soil drench could inhibit zoospore motility and reduce production of sporangia and viable zoospore cysts, thus reducing inoculum production and subsequent new infections by Phytophthora species.