Crop residue, in the food-safety sense, means the minute traces of pesticide or fertiliser that can remain on or in crops after harvest and carry through into the food chain. Residues arrive through approved spray programmes, drift from neighbouring fields, or soil uptake, and they may sit on the surface of fruit and vegetables or penetrate into the plant tissue. Regulators set maximum residue limits (MRLs) for each pesticide–crop combination, and consignments are checked against those limits at harvest, at import, and at retail. Washing, peeling, and processing can reduce some surface residues but not systemic ones. The term sits at the heart of modern produce safety: residues are unavoidable at low levels in conventional farming, so food law manages them through registration, good agricultural practice, and routine monitoring rather than demanding absolute zero.