What is a fungicide?

   A fungicide is a chemical substance used to kill small primitive organisms called fungi. Fungi cause many plant diseases, such as wheat rust and Dutch elm disease. They also attack many animals, including man. Common examples of human fungus infections include ringworm and athlete's foot. Certain fungi, particularly molds, damage leather, paper, foods, fabrics, and other plant or animal products.
   Fungicides are available in a variety of forms, depending on their use. Salves and ointments are widely used for fungus infections of the skin. Fungicides for crops are available in three forms: liquids, wettable powders, and dusts. Both liquids and wettable powders are mixed with water and are either sprayed directly on the plants or used to drench the soil. Dusts are applied to plants by dusting machines or are used to coat the plant seeds. Although fungicides destroy fungi, they do not harm the plants or animals on which they are applied. Plant fungicides are also harmless to any animals that may eat the treated plants.
   One of the most widely used plant fungicides is bordeaux mixture, whose components are copper sulfate and calcium hydroxide, or slaked lime. Solutions of sulfur and lime are also used extensively as plant fungicides. Ferbam, an iron compound, is often used in orchards, and a zinc compound called zineb is used on many fruits and vegetables.
   Animal fungus infections are frequently treated with various compounds of sulfur and iodine. Large doses of neomycin and other antibiotic drugs are also used in the treatment of fungus diseases.