Uptake of ethylenebis(dithiocarbamate) fungicides and ethylenethiourea by soybeans

Abstract

Radioactivity from soil treatments of 10 to 100 ppm of 14C-labeled ethylenebis(dithiocarbamate) (EBDC) fungicides (nabam, zineb, and maneb) and 0.1 to 10 ppm of ethylenethiourea (ETU), a degradation product, is readily absorbed by soybeans and translocated throughout the plant. The presence of ETU on soybean leaves after EBDC foliar treatments decreased rapidly from <20 ppm after 1 day to <2 ppm after 15 days in the greenhouse. ETU applied to leaves of soybeans, which were kept outdoors, decreased from an initial level of 27 ppm to <0.04 ppm after 14 days and was below detectable levels by 24 days. ETU content in soybeans from EBDC fungicide soil treatments remained low (<0.2 ppm) throughout the 15-day monitoring period. Methanol extract from leaves contained degradation products (7 to 10) common to both ETU and the EBDC's, as determined by thin-layer chromatography. Ethyleneurea was the major degradation product.Ethylenebis(dithiocarbamate) (EBDC) compounds, the most important fungicide class for protecting plants from destructive pathogens (Tweedy, 1973), have been extensively used since their introduction over 30 years ago.

Studies with manganese [14C]ethylenebis(dithiocarbamate) ([14C]maneb) fungicide and [14C]ethylenethiourea ([14C]ETU) in plants, soil, and water

“…No 14C residues at all were found in ripe tomatoes from any treatment (<0.01 ppm). These small total 14C-labeled residues, taken up by tomato plants from field-treated soil, are considerably less than the levels reported taken up by potted soybeans in a greenhouse test (Nash, 1975(Nash, ,1976, but our tests are closer to actual use conditions on a registered crop.…”

“…Trace amounts of ETU have been reported on EBDC-sprayed crops (Lyman, 1971; Lyman and LaCoste, 1975; Newsome et al, 1975;Nash, 1974Nash, , 1975Nash, ,1976Yip et al, 1971). In general, several of these workers and others have shown that ETU disappears rapidly from treated plants and soil (Blazquez, 1973;Hoagland and Freer, 1976; Kaufman and Fletcher, 1973).…”

Manganese ethylenebis(dithiocarbamate) (maneb)/ethylenethiourea (ETU) residue studies on five crops treated with ethylenebis(dithiocarbamate) (EBDC) fungicides

“…Although ETU itself is readily degraded to ethyleneurea, glycine, and other materials (Rhodes, 1977), trace amounts of ETU residues have been reported on EBDC sprayed crops (Lyman, 1971;Lyman and Lacoste, 1975;Newsome et al, 1975;Nash, 1974Nash, ,1975Nash, ,1976; Yip et al, 1971). The present studies were conducted to provide additional information on this question.…”

A method for the determination of ethyleneurea in foods as the pentafluorobenzamide

“…Ethyleneurea (2-imidazolidinone) is a reaction product of the ethylenebis(dithiocarbamates) (EBDCs) and represents a major metabolite of these fungicides. It has been identified in plants treated in the greenhouse with [uC]zineb (Vonk, 1976) or outdoors with [3H]mancozeb (Lyman, 1971) or [wC]maneb, [14C]zineb, [14C]nabam, and [14C]ETU (Nash, 1976). Ethylenethiourea (ETU), a transient metabolite of the EBDCs, is a precursor of ethyleneurea in vitro in the presence of light and photosensitizers (Ross and Crosby, 1973; Cruickshank and Jarrow, 1973) and in vivo in plants (Hoagland and Frear, 1976;Nash, 1976).…”