Foliar Sprays of Cyclaniliprole and Abamectin to Control Asian Citrus Psyllid and Citrus Leafminer on Orange: Fall, 2016

Huanglongbing or citrus greening is a devastating disease, transmitted by ACP, that causes decline in citrus tree health, vigor, and yield. The citrus leafminer can severely damage new shoots which facilitates the introduction of citrus canker disease. Insecticides with diverse modes of action are needed to slow the selection for insecticide resistance in these pests. This experiment was conducted at the Southwest Florida Research and Education Center in Immokalee Florida. ‘Hamlin’ trees bud grafted to ‘US-802’ (Citrus grandis × Poncirus trifoliata) planted in 2010 at a density of 308 trees/acre were treated on 4 Nov 2016. Applications were made using a Durand Wayland AF100-32 air-blast speed sprayer operating at 1.9 mph and 300 psi equipped with three #4 John Beane ceramic nozzles with a threehole, twohole, and twohole whirl plate behind each nozzle (top to bottom, respectively) delivering 100 gpa. Eight treatments were assigned to nine tree plots in an RCB with four blocks. Each block consisted of one tree row that was separated from other blocks by an untreated buffer row. All treatments except the check included 435 Oil. ACP density was evaluated 3 DAT, 6 DAT, and then weekly through 5 wk after treatment. On each date, ten randomly selected shoots per plot were collected and examined using a stereomicroscope in the laboratory to count ACP nymphs. CLM larvae were counted on the bottom leaves of these same shoots. The density of ACP adults was assessed on six trees per plot using the stem-tap sampling method twice on each tree. For each 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. Data were subjected to ANOVA with means separated using LSD (P = 0.05).

ACP density prior to treatment averaged 0.51 adults per tap. All treatments on 4 Nov, except for Harvanta at 11 oz/ac alone or with Abba Extra at 7.6 oz/ac, significantly lowered adult ACP numbers when compared with the untreated check, whereas all treatments provided significant suppression thenceforth through 29 Nov (Table 1). Similarly, all treatments reduced numbers of ACP nymphs compared with the untreated check on all sample dates through 6 Dec (Table 2). All treatments also reduced the number of CLM larvae when compared with the untreated check on all sample dates (Table 3).

No phytotoxicity was observed. This research was supported by industry gifts of pesticide and funds.