Chlorothalonil(2,4,5,6-tetrachloroisophthalonitrile) is an organic compound mainly used as a broad spectrum, nonsystemic fungicide, with other uses as a wood protectant, pesticide, acaricide, and to control mold, mildew, bacteria, algae. It is a protective fungicide, and it attacks the nerve system of insects and mites, causing paralysis within hours. The paralysis can not be reversed.