Abstract: 【Aim】 To determine a scientific and reasonable method of ozone (O₃) water to control the chive gnat, Bradysia odoriphaga, and to make maximum use of it. 【Methods】 A series of concentrations of O₃ water (10, 15, 20 and 30 mg/L) were irrigated into the Chinese chive (Allium tuberosum) outdoor fields. Three concentrations of O₃ water (5, 10 and 15 mg/L) were irrigated into the Chinese chive fields covered with plastic film on the ground and with arch plastic shed. Different developmental stages of B. odoriphaga (adult, larva and pupa) and plants of Chinese chives were treated with ozone water (10-15 mg/L), and Chinese chive seeds were soaked with O₃ water (2 and 10 mg/L) in the laboratory. Then, the control efficacy of ozone water against B. odoriphaga was assayed, and the influences of ozone water on the growth and seed germination of Chinese chives were evaluated. 【Results】 O₃ water irrigated at the concentration of 10-15 mg/L in Chinese chive fields covered with plastic film had a significant control efficacy against B. odoriphaga, even as high as 100%. However, O₃ water irrigated in open fields had no obvious control efficacy on B. odoriphaga. O₃ water irrigated in Chinese chive fields of various cultivation types did not aggravate the damage of Chinese chives by B. odoriphaga. In the laboratory conditions, ozone water led to malformation or death of adults, larvae and pupae, even the body surface was corroded obviously. O₃ water promoted the early growth of Chinese chives, increased the plant height, but was not conducive to regerminate new roots or grow the clipped fibrous roots. When the seeds of Chinese chives were soaked with O₃ water and then washed instantly with clean water, they normally germinated. However, when the seeds were soaked with O₃ water but not washed with clean water, the seed germination was seriously inhibited. 【Conclusion】 Control of B. odoriphaga with ozone water is worthy to be recommended, and the highest efficiency can be achieved under closed conditions.

Key words: Bradysia odoriphaga, Allium tuberosum, ozone water, germination, plastic covering, outdoor fields, field experiment