Abstract
Thermal degradation of benomyl in the fungicide Benlate DF® at temperatures higher than 55°C leads to the formation of N,N′-dibutylurea (DBU). External moisture is not required, since starch, an “inert” ingredient in the formulation, serves as a source of water. Enhanced phytotoxicity of the heat-treated, DBU-rich Benlate DF® was demonstrated by lettuce seedling bioassay. Temperatures higher than 70°C were recorded in a metal shipping container in June 1995 in Hawaii. Accumulation of DBU was observed in Benlate DF® sealed in ampules and stored in this container. It is concluded that DBU formation is an intrinsic characteristic of Benlate DF® at the temperatures tested. High temperature and high humidity in tropical regions provide ideal conditions for DBU formation in Benlate DF®.
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References
Aragaki M, Uchida JY, Kadooka CY (1994) Toxicity of Benlate® to cucumber and evidence for a volatile phytotoxic decomposition product. Achiv Environ Contam Toxicol 27:121–125
ASA Institute (1990) SAS/STAT user's guide, version 6, vol 2, 4th ed. SAS Inst, Cary, NC
Bartolomei M, Cignitti M, Cotta-Ramusino M, Iela MT, Soccorsi L (1994) Solid-phase thermal decomposition of benomyl. Pestic Sci 41:91–95
Chiba M (1977) Effects of temperature on the equilibrium of benomyl and its degradation products methyl 2-benzimidazole carbamate and n-butyl isocyanate in benzene and chloroform. Bull Environ Contam Toxical 14:285–290
Chiba M, Doornbos F (1974) Instability of benomyl in various conditions. Bull Environ Contam Toxical 11:273–274
Clark Jr. JM, Switzer RL (1977). In: Experimental biochemistry, 2nd ed. W.H. Freeman, San Francisco, p 4
Department of Business Economic Development and Tourism, State of Hawaii (1994). The State of Hawaii Data Book.
Hammerschlag RS, Sisler HD (1973) Benomyl and methyl-2-benzimidazole carbamate (MBC): Biochemical, cytological and chemical aspects of toxicity in Ustilago maydis and Saccharomyces cerevisiae. Pestic Biochem Physiol 3:42–54
Leach HW (1965) Gelatinization of starch. In: Whistler RL, Paschall EF (eds) Starch: Chemistry and technology. Vol. 1. Fundamental Aspects. Academic Press, New York, pp 289–306
Moye HA, Schilling DG, Aldrich HC, Gander JE, Buszko M, Toth JP, Brey WS, Bechtel B, Tolson JK (1994) N,N-Dibutylurea from n-butyl isocyanate, a degradation product of benomyl. 1. Formation in Benlate® formulations and on plants. J Agric Food Chem 42:1204–1208
Schilling DG, Aldrich HC, Moye HA, Gaffney JF, Tolson JK, Querns R, Mossler MA, Russell BL (1994) N,N-Dibutylurea from n-butyl isocyanate, a degradation product of benomyl. 2. Effects on plant growth and physiology. J Agric Food Chem 42:1209–1212
Tang CS, Yanagihara K, Zhang Y (1992) 1-Butyl isocyanate from aqueous Benlate® formulations. Achiv Environ Contam Toxicol 24:270–272
Tang CS, Zhang Y, Yee ABK, Yanagihara K (1993) Effect of temperature on the evolution of n-butyl isocyanate from aqueous Benlate® formulations. Achiv Environ Contam Toxicol 25:516–519
Uchida JY, Kadooka CY, Aragaki M (1993) Phytotoxicity caused by Benlate® and differences among production lots. Phytopathology 83:1385 (Abstract no. 483)
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Tang, C.S., Song, L.W. Spontaneous N,N′-dibutylurea (DBU) formation in benlate DF® formulation under elevated temperatures. Arch. Environ. Contam. Toxicol. 30, 403–406 (1996). https://doi.org/10.1007/BF00212300
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DOI: https://doi.org/10.1007/BF00212300