Investigations for residues of dithiocarbamates and ethylenethiourea (ETU) in different crops [cucumbers, carrots, grain and straw of wheat, potatoes, lettuce, black currants, fruits, vegetables, Denmark]

In 1963 and 1973-76 experiments have been carried out on the disappearance of the ethylenbisdithiocarbamates maneb, mancozeb, metiram, zineb and the propylen compound propineb in different crops. In addition residues of ETU have been determined in some of the crops. By the treatments the conditions of the experiments were in accordance with practical usage, except for wheat and lettuce where dosages larger than normally applied were also used. Dithiocarbamates: Residues found in cucumbers were 0.2-1 mg/kg, depending on time for sampling. By normal dosages the residues in grains of wheat with few exceptions were less than 0.30 mg/kg with 36 days between treatment and sampling. The corresponding value of straw of wheat were 8 mg/kg. The residues found in carrots, potatoes and lettuce grown in the summer season with one exception from each crop were below the limit of determination. In lettuce grown in the winter season the residues in fully developed plants 91 and 63 days after a treatment with normal dosage carried out 11 and 39 days after planting were less than 0.6 and 8 mg/kg. The residues found in black currants were 2-50 mg/kg, depending on time and number of treatments. Ethylenethiourea (ETU): Residues found in grains of wheat were maximum 0.05 mg/kg in samples with treatment 2 days before harvest. In lettuce grown in the winter season the residues in fully developed plants 91 and 63 days after a treatment with normal dosage carried out 11 and 39 days after planting were from below limit of determination to 0.06 mg/kg. Presented are also results of residues of dithiocarbamates in Danish produced and imported fruits and vegetables from the years 1975-78. After the performance of the above mentioned experiments new Danish regulations for use of mancozeb, maneb, propineb and zineb to fruits, vegetables, corn and potatoes became valid from January 1, 1978.