Publications - Faculty - Recently Submitted Faculty Publications 2008
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Stelinski - Journal of Economic Entomology
Effect of Spray Droplet Size on Mortality of Asian Citrus Psyllid (Hemiptera: Psyllidae)
DHANA RAJ BOINA, MASOUD SALYANI and LUKASZ L. STELINSKI
Abstract: In this laboratory investigation, we determined the effect of spray droplet size on mortality of three life stages of Diaphorina citri Kuwayama (Hemiptera: Psyllidae). Six nearly uniform spray droplet sizes (40.5, 52.0, 101.5, 147.9, 174.0, and 264.7 μm mean diameter) of fenpropathrin, a synthetic pyrethroid, were generated using a droplet generator equipped with piezo-electric nozzles. Fenpropathrin was tested at 68.1 and 102.2 g active ingredient (AI)/acre rates which were equivalent to ½ and ¾ of the recommended field rates, respectively. This resulted in delivery of 0.38 or 0.58 mg AI/min at low (20.8-130.7 droplets/cm2) or high (81.3-327.2 droplets/cm2) droplet densities onto target plants that were moving at 7.2 or 27.2 cm/s. In general, percent mortality of D. citri eggs, nymphs, and adults decreased as the droplet size increased from 40.5 to 264.7 µm at 3 and 7 d posttreatment regardless of the deposition rate (0.38 or 0.58 mg AI/min) and droplet density (20.8-130.7 or 81.3-327.2 droplets/cm2) combination tested. The 40.5 and 52.0 µm droplets resulted in significantly greater mortality of D. citri than the 174.0 and 264.7 µm droplets. Droplets 101.5 and 147.9 µm in size resulted in mortality of D. citri ranging between 22-100%, irrespective of deposition rate and droplet density. With few exceptions, the 0.58 mg AI/min rate resulted in significantly greater mortality of D. citri than the 0.38 mg AI/min rate at 3 and 7 d posttreatment for all droplet sizes tested. Droplet density did not significantly affect mortality of D. citri at the 0.58 mg AI/min rate for all droplet sizes tested and at the 0.38 mg AI/min rate for droplets 147.9, 174.0, and 264.7 µm in size. Overall, our laboratory results indicate that applications of fenpropathrin at droplet sizes ranging between 40 and 150 µm should effectively control D. citri in citrus.
