Comparison of Senstar to Commercially Available Insecticides for Control of Asian Citrus Psyllid on Orange, Summer 2020

The Asian citrus psyllid’s (ACP) role in vectoring the citrus greening disease makes it the key pest of citrus grown in Florida. Chemical control is relied upon for controlling ACP, and new formulations and diverse modes of action are needed for rotational programs to slow insecticide resistance and the spread of the disease. This trial was conducted in a 6-yr-old citrus block at the Southwest Florida Research and Education Center planted with ‘Valencia’ orange trees at a plant density of 308 per acre. Young shoots needed for ACP reproduction were induced by mechanical pruning approximately 2 wk before sprays were initiated. Five treatments plus an untreated check were assigned to six-tree plots in an RCB design experiment with four blocks that were each contained within two rows of trees, allowing each treated row to be separated by an untreated buffer. Treatments were applied on 29 September using a Durand Wayland AF100-32 air blast speed sprayer operating at 1.9 mph and 300 psi equipped with four 4 John Beane ceramic nozzles delivering 115 gpa. Adult populations were monitored on 4 trees per plot by conducting a standard ‘tap’ sample four times on each tree on 2, 6, 13, 20, and 27 October. For each tap sample, adults were counted on a white plastic clipboard placed under a randomly chosen limb struck three times with a short length of PVC pipe. On each evaluation date, the number of nymphs were counted on each of ten randomly selected shoots per plot with the aid of a stereomicroscope in the laboratory.

Data were subjected to ANOVA with means separated using LSD (P = 0.05).

Prior to treatment, there was a low ACP density of 0.23 ± 0.41 (mean ± SE) ACP adults per tap on 28 Sep. After applications were made, all treatments reduced ACP adults compared with the untreated check from 7 to 28 DAT (Table 1). Similarly, all treatments reduced the density of nymphs on all sample dates when compared with the untreated check (Table 2). There were no significant differences in the density of adults or nymphs between treatments. No phytotoxicity was observed.¹

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