Record Details
Fungitoxicity of sodium n-methyldithio-carbamate (Vapam) and its decomposition products
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Fungitoxicity of sodium n-methyldithio-carbamate (Vapam) and its decomposition products |
| Names |
Elson, Joseph Earl
(creator) Corden, Malcom E. (advisor) |
| Date Issued | 1965-12-14 (iso8601) |
| Note | Graduation date: 1966 |
| Abstract | An assay for fungicidal activity of sodium N-methyldithiocarbamate (Na-MDC) and its decomposition products was developed in which there was a minimum influence due to the widely varying physical properties of the compounds (i.e. vapor pressure and water solubility). Decomposition of the toxicant during the tests was measured and held to a minimum. Tests were made against Fusarium oxysporum f. lycopersici (Sacc.) Snyd. & Hans. under aerobic and anaerobic conditions. Under anaerobic conditions Na-MDC gave a bimodal dosage response (DR) curve. Vapam, a commercial preparation of Na-MDC, failed to give bimodal DR curve although it did produce a two phase curve. Under aerobic conditions both forms of NaMDC gave straight line DR curves. Methyl isothiocyanate (MIT) produced identical DR curves under aerobic and anaerobic conditions, and thus, must have a different mode of fungicidal action from Na-MDC. There was no decomposition of Na-MDC or MIT during the test period so toxicity differences must be due to the action of the chemicals per se. N, N'-dimethylthiuram disulfide was highly fungitoxic and along with sodium trithiocarbonate, 2, 4-dimethyl-1, 2, 4-thiadiazolidine-3, 5-dithione and 4-methyl-5-methylimino-1, 2, 4-dithiazolidine-3-thione could account for the fungicidal effectiveness of Vapam. However, these compounds are not sufficiently volatile to explain the movement of the toxic principle from Vapam. Carbonyl sulfide, carbon disulfide, hydrogen sulfide, methylamine, N-N'-dimethylthiourea, and sulfur were not sufficiently fungicidal to account for the effectiveness of Vapam in plant disease control. Young spores from an acid culture medium were less susceptible to MIT in buffer than in water. When older cells from a basic culture medium were used the buffer increased the susceptibility of the cells to MIT. Although MIT is probably the main toxic agent from Vapam, this study shows that other decomposition products may contribute to its overall fungicidal activity. |
| Genre | Thesis/Dissertation |
| Topic | Fungicides |
| Identifier | http://hdl.handle.net/1957/47871 |
