Herbicides and Fungicides

Herbicides and Fungicides constitute major pesticide use classes with distinct toxicological profiles from insecticides. This topic is essential for Zambian tertiary students in agriculture, environmental science, and toxicology to understand the broad-spectrum chemicals used for weed and fungal control. The topic covers major herbicide groups: phenoxy acids (e.g., 2,4-D), triazines (e.g., atrazine), bipyridyls (e.g., paraquat), and their mechanisms, which often target plant-specific biochemical pathways, contributing to selective toxicity. The extreme human toxicity of paraquat (lung fibrosis) is examined in detail. For fungicides, classes like chlorothalonil and dithiocarbamates (e.g., maneb) are discussed, including concerns about environmental persistence, contamination of water supplies, and the generation of toxic metabolites like ethylenethiourea (ETU). Understanding the human health risks (ranging from irritation to carcinogenicity), environmental fate, and regulatory aspects of these agrochemicals is crucial for university examination performance and for promoting sustainable and safe agricultural practices in Zambia.