Mepiquat chloride is a synthetic plant growth regulator that is absorbed by the foliage and translocated throughout the plant. It is widely used to manipulate plant structure and helps to combat excessive vegetative growth which if left uncontrolled can lead to undesirable fruit shed boll rot and yield reductions. Mepiquat chloride inhibits gibberellic acid synthesis thus reducing cell enlargement and cell division rate. Application of mepiquat chloride in cotton results in a more compact plant caused by shortened internode elongation reduced main stem nodes and decreased leaf expansion and leaf area. Mepiquat chloride is approved for use in European Union (EU) following Regulation (EC) No 1107/2009 (repealing Directive 91/414/EEC). The maximum residue level (MRL) for Mepiquat (sum of mepiquat and its salts expressed as mepiquat chloride) is established from 0,02 to 4 mg/kg for many plant-based products and 40 mg/kg for linseed mustard sunflower and poppy seeds. For products of animal origin the MRL is set from 0,05 to 0,8 mg/kg as per Reg. (EU) 2021/976. Mepiquat has to be monitored in the Multiannual Control Programme for Pesticides Residues (MACP) run within the EU and EFTA in/on products of plant origin.