Effects of different auxiliaries, spray nozzles and spray pressures of self-propelled boom sprayer on spray effect in paddy field

In this study, the effects of six spraying auxiliaries(Red Sun, Pele, Maisi, Rongtou, Neem Oil and Hasuteng), three types of spray nozzles(TEEJET-VP80015, ASJ-VP110015 and LICHENG-VP11003) and three types of spraying pressures(0.2, 0.4, 0.6 MPa) on pesticide utilization rate of deposition, the atomization performance (D₅₀, droplet density, etc.), spray droplet distribution uniformity and the control efficiency of 240 g/L thifluzamide SC on rice sheath blight disease and rice yields were studied by YIFENG-MARUYAMA 3WP-500CN self-propelled boom sprayer in field test and using the Allura Red AC 85 as an indicator. The results indicated that the spray droplet distribution uniformity of Hasuteng was significantly higher than that of other auxiliaries under the condition of the TEEJET-VP80015 nozzle and 0.4 MPa spray pressure, which of the coefficient of variation reached 0.11, meanwhile the effects on the estimated deposition of droplets(45.74 μL/cm²) and span of distribution(1.29) were significantly higher than those of other auxiliaries; The effect of auxiliary Maisi on the density of droplets(103.78 droplet/cm²) and utilization rate of pesticide deposition(83.88%) were significantly higher than those of other auxiliaries. Different pressures using the TEEJET-VP80015 nozzle had significant effect on span of distribution, adherence rate of droplets and utilization rate of pesticide deposition without auxiliaries, and the span of distribution, the adherence rate of droplets and the utilization rate of pesticide deposition reached 1.18, 33.32%, and 78.19% respectively when the pressure was set for 0.6 MPa. When without auxiliaries and under the condition of 0.4 MPa, the LICHENG-VP11003 nozzle displayed a greater influence on the spray droplet distribution uniformity, and was significantly higher than that of the other two nozzles, which of the coefficient of variation was 0.12, had a greater impact on the coverage (69.37%), estimated deposition of droplet(42.77 μL/cm²) and utilization rate of pesticide deposition (75.79%) were significantly higher than those of the other two nozzles. The effect of control efficacy of 240 g/L thifluzamide SC on the rice sheath blight disease was consistent with the results of the performance and atomization quality of deposition droplets. The control efficiency of adding the auxiliary Maisi on sheath blight was significantly higher than that of adding other auxiliaries, reached 89.27%.When increasing the spray pressure to 0.6 MPa, the control efficiency was promoted to 88.67%, which was significantly higher than other pressures. When using TEEJET-VP80015 nozzle and under the conditions of 0.4 MPa spray pressure, the rice yield reached 8301 kg/hm², which was significantly higher than artificial spraying. Therefore, the auxiliaries and the spray nozzles have produced a significant impact on the utilization rate of pesticide deposition, uniformity of the droplets, atomization quality of deposition droplets of self-propelled boom sprayer, and the control efficiency of pesticides can be improved by adding auxiliaries under appropriate spray pressure.