Arthropod Management Tests 2014, Vol. 39 doi: 10.4182/amt.2014.D16 (D16) ORANGE: Citrus sinensis (L.) Osbeck, ‘Hamlin” SOIL DRENCH APLICATIONS OF INSECTICIDES FOR CONTROL OF ASIAN CITRUS PSYLLID AND CITRUS LEAFMINER 2013 Philip A. Stansly University of Florida/ IFAS Southwest Florida Res. and Ed. Center 2686 State Road 29 North Immokalee, FL 34142-9515 Phone: (239) 658-3400 Fax: (239) 658-3469 Email: [email protected], Barry Kostyk Email: [email protected] Asian citrus psyllid (ACP): Diaphorina citri Kuwayama Citrus leafminer (CLM): Phyllocnistis citrella Stainton ACP is a key citrus pest in Florida, attacking young flush and spreading the devastating huanglongbing (HLB) or citrus greening disease. Mining by CLM exacerbates citrus canker disease. Young trees flush often and therefore require constant protection afforded by systemic insecticides applied as soil drenches. The objectives of this trial were to compare drenches of 2 neonicontinoids and one non-neonicotinoid to the standard imidacloprid. Two-year old ‘Hamlin’ orange trees spaced 10 ft apart within rows spaced at 22 ft or 198 trees per acre were used at the University of Florida Southwest Florida Research and Education Center in Immokalee, Florida. Rates used were based on a density of 180 trees per acre. Seven treatments were assigned to 5 tree plots in an RCB design with 4 replicates. Weeds, debris and leaf litter were removed from beneath each tree prior to application. An 8 oz suspension of each product was applied 20 May to bare soil within 8 inches of the trunk using an EZ-Dose® sprayer operating at 45 psi. Due to heavy rains preceding the applications irrigation was not used prior to or after treatment. The adult psyllid population was monitored on 28 May 5, 11, 19, 26 Jun and 3 Jul the by striking a randomly chosen branch 3 times with a length of PVC pipe on each of the 5 trees in each plot to dislodge insects onto a white plastic clipboard to be counted as one tap sample. At the same time five shoots were removed from each plot and examined for ACP nymphs in the laboratory using a stereomicroscope. The numbers of leafminer larvae were counted on the bottom three leaves of each shoot. Data were analyzed by LSD contingent of a significant F (P = 0.05) value. Significant treatment effects on adult psyllids were not seen until 11 Jun, 19 days after treatment (DAT), with a lapse again on 19 Jun (Table 1). Most reduction was observed with Belay through 3 Jul followed by Venom and Admire Pro which persisted through 11 and 26 Jun respectively. Significant suppression of adults compared to the check was seen only with the 20.8 oz rate of Beleaf and only on 26-Jun. Significant treatment effects on nymphs were seen on all sample dates first with Belay on 28 May then Admire Pro and Venom at 5 Jun. Belay again provided the greatest and most persistent reduction of nymphs through 3 Jul, significantly greater than Admire Pro and Venom which lost activity at least 2 weeks earlier. The high rate of Beleaf showed activity on 19 and 26 Jun. Suppression of CLM was seen from all products on 28 May, all but the two lower rates of Beleaf on 5 Jun, but only Admire Pro on 11 Jun (Table 3). A 1.57 inch rainfall registered at the Immokalee FAWN weather station the afternoon of the application likely leached product from the root zone and reduced effectiveness of all neonicotinoid treatments in proportion to their solubility in water. This research was supported by industry gifts of funding and insecticides. 1 Arthropod Management Tests 2014, Vol. 39 doi: 10.4182/amt.2014.D16 Table 1 Adults per tap Product/ Formulation Rate amt/acre Untreated Check Admire Pro 4.6 SC 7.0 oz Belay 2.13 SC 6.0 oz Venom 70 SG 3.0 oz Beleaf 50 SG 6.3 oz Beleaf 50 SG 12.6 oz Beleaf 50 SG 20.8 oz 28-May 5-Jun 11-Jun 19-Jun 2.50 1.70 0.90 0.80 2.25 1.55 1.40 3.10 2.50 1.80 3.00 4.05 4.50 1.55 3.65a 1.00c 0.70c 1.60bc 2.50ab 2.30b 2.40ab 1.45 1.10 0.50 1.00 1.00 1.35 0.90 26-Jun 3-Jul 1.40a 0.45cd 0.40cd 0.25d 1.05abc 1.20ab 0.50bcd 1.50ab 1.00bc 0.20c 0.70bc 1.20ab 1.90a 0.70bc Means within columns followed by same or no letter are not statistically different (LSD, P>0.05). Table 2 Nymphs per flush Product/ Formulation Untreated Admire Pro 4.6 SC Belay 2.13 SC Venom 70 SG Beleaf 50 SG Beleaf 50 SG Beleaf 50 SG Rate amt/acre 7.0 oz 6.0 oz 3.0 oz 6.3 oz 12.6 oz 20.8 oz 28-May 5-Jun 11-Jun 19-Jun 50.50abc 71.53a 12.00d 43.76abc 22.33cd 56.53ab 36.13bcd 22.84a 15.88ab 50.15a 4.75b 2.85c 24.40b 3.05b 1.68c 6.11c 5.05b 7.85bc 18.81bc 26.61a 18.80a 53.4a 10.65b 17.05a 28.25b 31.30a 7.80bc 21.13bc 26-Jun 3-Jul 58.50a 40.20ab 9.78c 43.95ab 48.70ab 34.00b 36.25b 40.95a 21.15bc 14.15c 32.44ab 40.21a 33.21ab 27.85abc Means within columns followed by same letter are not statistically different (LSD, P>0.05). Table 3 Leafminer Larvae/3 leaves Product/ Formulation Rate amt/acre 28-May 5-Jun 11-Jun Untreated Admire Pro 4.6 SC Belay 2.13 SC Venom 70 SG Beleaf 50 SG Beleaf 50 SG Beleaf 50 SG 7.0 oz 6.0 oz 3.0 oz 6.3 oz 12.6 oz 20.8 oz 6.29a 0.64d 1.17cd 1.88bcd 3.20bc 3.67b 3.10bc 3.82a 1.80bc 1.15c 2.40bc 3.17ab 2.45abc 1.60c 0.75ab 0.00c 0.25bc 0.45bc 1.07a 0.70ab 0.53abc Means within columns followed by same letter are not statistically different (LSD, P>0.05). 2
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