Abstract:  【Aim】 To determine the optimum irrigation period and application condition for controlling the larvae of the chive maggot, Bradysia odoriphaga, scientifically and rationally with irrigating ozone (O₃) water. 【Methods】 We investigated the control efficacy of different concentrations of O₃ water (5, 10, 20 and 30 mg/L) against B. odoriphaga larvae, the control efficacy of 30 mg/L O₃ water against B. odoriphaga larvae in flat land covered with plastic film under different sunlight intensities, in three different irrigation conditions (flat land covered with plastic film, small arch plastic shed, and small arch plastic shed covered with petates), and at various irrigation frequencies of 30 mg/L O₃ water under two different irrigation environments (flat land covered with plastic film and small arch plastic shed), respectively. And we also investigated the effects of 30 mg/L O₃ water on the yield and root growth of Chinese chives in flat land covered with plastic film. In addition, we analyzed the influence of sunlight intensity on soil temperatures and the control efficacy of irrigating ozone water under different irrigation environments. 【Results】 In the flat land covered with plastic film, the optimum concentration of O₃ water for the control against B. odoriphaga larvae was 20-30 mg/L. In treatments of irrigating 30 mg/L O₃ water to flat land covered with plastic film, the control efficacy of O₃ water against B. odoriphaga larvae was positively related to the sunlight intensity on the day of O₃ water irrigation, the larval mortality of B. odoriphaga was up to 100% at 1 d after irrigation when the sunlight intensity was over 60 000 lx, while no significant control efficacy was found when the sunlight intensity was below 10 000 lx. When the sunlight intensity was moderate, the prevention and control efficacy of 30 mg/L O₃ water against B. odoriphaga larvae was poor in the early stage, and gradually enhanced in the late stage. The effect of soil warming was positively correlated with sunlight intensity and significantly related with irrigation environments. The temperature of5 cmdeep soil under different irrigation conditions was as follows: flat land covered with plastic film> small arch plastic shed> small arch plastic shed covered with petates. The control efficacy of O₃ water irrigated into the small arch plastic shed against B. odoriphaga larvae was significantly higher than that irrigated into the flat land covered with plastic film and that irrigated into the small arch plastic shed covered with petates. Repeatedly continuous irrigating of O₃ water could improve the control efficacy of O₃ water against B. odoriphaga larvae, and the control efficacy in the small arch plastic shed was more remarkable. When O₃ water was irrigated, the distance between the inlet and the end of the farmland should not exceed40 m. After irrigating 30 mg/L O₃ water in the plat land covered with plastic film, the plant height, weight and the number of fibrous roots of Chinese chives were significantly higher than those of the control (irrigating water), but the number of tillers per cluster of Chinese chive showed no significant difference from the control. 【Conclusion】 When the O₃ water is irrigated scientifically and reasonably, it not only shows ideal control efficacy against B. odoriphaga larvae, but also can promote the growth of Chinese chives.

Key words: Bradysia odoriphaga, Chinese chives, ozone water, flat land covered with plastic film, small arch plastic shed, sunlight intensity