Residues of the algicide endothal in water, soil and rice, after paddy field applications

摘要

AbstractIn order to obtain residue data from the application of the algicide endothal in Italian rice paddy fields, two experiments were carried out using a 50 g kg−1granular formulation in a small pond and the same granular and two liquid formulations in actual paddy fields of the Italian rice growing area.Endothal decay in the pond water was very rapid, reaching residue levels of 0·01‐1·02 mg litre−1in two days and 0·004‐0·01 mg litre−1at the third day. The muddy soil of the pond was free from measurable endothal residues(<0·02 mg kg−1). In the paddy‐field waters, the endothal decay was slower, with an average half‐life time of 3·3 days, independently of the type of formulation. The actual residues in water after 6 days ranged from 0·3 to 1·3 mg litre−1according to the initial amount of product applied, and, consequently, to the initial concentration in water.Rice samples collected at the normal harvest time from the two paddy fields, treated with three different formulations, showed no endothal residue at the minimum detecta