: an agent that destroys fungi or inhibits their growth
Any toxin used to kill or inhibit growth of fungi (seefungus) that cause economic damage to crop or ornamental plants (including rusts in cereals, blight in potatoes, mildew in fruits) or endanger the health of domestic animals or humans. Most are applied as sprays or dusts; seed fungicides are applied as a protective coating to seeds before germination. Copper compounds, especially copper sulfate mixed with lime and water (Bordeaux mixture), and sulfur have long been used for this purpose, but now synthetic organic compounds are commonly used. Many antifungal substances occur naturally in plant tissues.