A study was undertaken to evaluate the decline of the residues of pyridalyl in tomatoes grown in two different cultivation systems: open field (conventional cultivation) and net house (pot experiment). Field experiment was conducted with commercial (10 EC) and nanoformulation of pyridalyl on tomato crop. Tomato plants were subjected to pesticide spray, when fruits were close to ripeness. Fruit samples were taken periodically and cleaned up using QuEChERS methodology, and the residue of pyridalyl was analyzed by ultrahigh-performance liquid chromatography (UHPLC). It dissipated in tomato fruit following the first-order kinetics. In field, average initial deposit of pyridalyl in tomato was observed to be 0.222 and 0.371 μg g(-1) at recommended and double the recommended application rate, respectively, using nanoformulation while it was 0.223 and 0.393 μg g(-1) on using commercial formulation, respectively. The half-life (t1/2) value of nanopyridalyl in tomato fruit was 2.8 and 3.2 days while for commercial formulation, it was 2.5 and 2.6 days for recommended and double the recommended dose, respectively. In India, maximum residue limit (MRL) on tomato has not been fixed for pyridalyl but its residues were always below European MRLs (5 μg g(-1)) on tomato at both application rates. The results of terminal residue showed that pyridalyl residues were below the available MRL. Low residues in tomatoes suggested that this pesticide is safe to use under the recommended dosage. No statistical differences were observed between the cultivation systems in relation to the residue levels of pyridalyl.