Thiophanate-methyl

Thiophanate-methyl is a fungicide widely used in agriculture to control a broad spectrum of fungal diseases. It is a systemic fungicide, meaning it is absorbed by the plant and can move from the site of application to other parts of the plant. Thiophanate-methyl is a member of the benzimidazole class of fungicides and works by inhibiting cell division in the fungi.

Chemical Structure and Properties

Thiophanate-methyl is a methyl ester of dimethyl 4,4'-(o-phenylene)bis(3-thioallophanate). It is a white crystalline solid with a slight sulfurous odor. It is moderately soluble in water and readily soluble in most organic solvents. The chemical formula for thiophanate-methyl is C12H14N4O4S2.

Mode of Action

Thiophanate-methyl inhibits the process of mitosis in fungal cells by disrupting the formation of the mitotic spindle, which is essential for cell division. This prevents the fungi from growing and reproducing, effectively controlling the disease.

Uses

Thiophanate-methyl is used to control a wide range of fungal diseases in a variety of crops, including fruits, vegetables, ornamentals, and cereals. It is effective against diseases such as powdery mildew, gray mold, and apple scab.

Safety and Environmental Impact

Thiophanate-methyl is of low toxicity to humans and animals. However, it can cause irritation to the eyes and skin, and prolonged exposure can lead to allergic reactions. It is moderately toxic to fish and other aquatic organisms. Thiophanate-methyl is not persistent in the environment and is rapidly degraded by microbes in the soil.

Regulation

In the European Union, thiophanate-methyl has been classified as a potential endocrine disruptor and its use has been restricted since 2020. In the United States, it is classified as a General Use Pesticide (GUP) by the Environmental Protection Agency (EPA).