Comparison of Utilization Rates and Droplets Distributionof Pesticides Sprayed by Electric and ManualSprayers in Rice Fields

【Objective】The effective utilization rates and droplets distribution effects of three pesticides sprayed on rice by manual sprayer and electric sprayer were compared.【Method】The plot experiments were carried out on pesticide utilization rate of late rice in two towns of Huiyang District and two towns of Boluo County of Guangdong Province. The tested pesticides included 50% pymetrozine water dispersible granule (WDG), 5% chlorpromazide suspension concentrate (SC) and 2% kasugamycin aqueous solutions (AS), and the allura red tracers were added into the pesticide diluents. Five point sampling method, droplet cards and spectrophotometer (501nm) were used in the research.【Results】The utilization rates of pymetrozine, chlorobenzamide and kasugamycin on rice sprayed by electric sprayers were 39.43%, 38.03% and 38.98%, respectively; while the rates by manual sprayers were 29.02%, 28.08% and 28.50%, respectively. Compared with those of the manual sprayer treatment, the effective deposition rates of three pesticides sprayed by the electric sprayer increased by 10.41, 9.95 and 10.93 percentage points, respectively. Moreover, the effective deposition rates of the electric sprayer treatments were significantly higher than those of the manual spray treatments. The results of droplets deposition distribution assay indicated that, both of manual and electric sprayer treatments decreased gradually from top to bottom, and droplet deposition of different layers showed significant differences. The results of droplets diameter showed that, the droplets diameters of middle and lower layers on rice under the manual sprayer treatments were significantly higher than those of the electric sprayer treatments. The results of droplets quantity indicated that, the electric sprayer treatments showed a downward trend from bottom to top, and the droplet quantities of the electric sprayer treatments were also higher than those of the manual sprayer treatments.【Conclusion】 The effective utilization rates of three pesticides sprayed by electric sprayers were higher than 38% at the heading stage of late rice in Guangdong Province, which were 9.95-10.41 percentage points higher than those of manual sprayer treatments. And the atomization effect of electric sprayer was better than that of manual sprayer.