Mancozeb is a dithiocarbamate non-systemic agricultural fungicide with multi-site, protective action on contact. It is a combination of two other dithiocarbamates: maneb and zineb.^[1] The mixture controls many fungal diseases in a wide range of field crops, fruits, nuts, vegetables, and ornamentals. It is marketed as Penncozeb, Trimanoc, Vondozeb, Dithane, Manzeb, Nemispot, and Manzane. In Canada, a mixture of zoxamide and mancozeb was registered for control of the mildew named Gavel as early as 2008.^[2]

Mechanism

Mancozeb reacts with, and inactivates, the sulfhydryl groups of amino acids and enzymes within fungal cells, resulting in disruption of lipid metabolism, respiration, and production of adenosine triphosphate.^[3]

Mancozeb is listed under FRAC code M:03 The "M:" refers to Chemicals with Multi-Site Activity. "M:" FRAC groups are defined as generally considered as a low risk group without any signs of resistance developing to the fungicides.^[4]

Toxicology

A major toxicological concern is ethylenethiourea (ETU), an industrial contaminant and a breakdown product of mancozeb and other EBDC pesticides. It has potential to cause goiter, a condition in which the thyroid gland is enlarged and has produced birth defects and cancer in experimental animals. ETU has been classified as a probable human carcinogen by the EPA.^[5] Mancozeb has been shown to have significant negative effects on beneficial root fungi - totally preventing spore germination at levels far below recommended dosage levels.^[6]