INSECTICIDAL CONTROL OF ASIAN CITRUS PSYLLID THROUGH FOLIAR APPLICATIONS ON ORANGE, 2006

ACP is an important pest of citrus. Nymphs and adults suck sap from the young leaves and are also capable of carrying and transmitting the bacterium responsible for the citrus greening or huanglongbing disease. Therefore, reduction in ACP populations is required to reduce the spread of this disease. The study was carried out at the Southwest Florida Research and Education Center (SWFREC), Immokalee, Florida in Sep 2006. The experimental block consisted of 12-yr-old sweet orange Citrus sinensis (L) Osbeck ‘Valencia’ trees planted on double-row raised beds at a density of 133 trees/acre. Trees were irrigated by micro-sprinklers and subjected to conventional cultural practices. Bed sides of the experimental trees were pruned with a tractor-mounted box blade mower to induce new flush and encourage psyllid infestation. Nine treatments including an untreated check were randomly distributed across 4 replicates, each of which consisted of 3 rows of 21 trees each interspersed with 3 buffer rows. Treatments were applied on 8 Sep 2006 to the bed side of the trees using a tractor mounted Durand Wayland 3P-10C-32 air blast speed sprayer with an array of seven # 5 T-Jet stainless steel cone nozzles per side operating at a pressure of 200 psi delivering 150 gpa at a tractor speed of 1.5 mph. Data were taken from four trees in the center of each plot. Pre treatment data were collected one day before application, and post treatment data were collected 3, 10, and 18 DAT. Ten randomly selected flushes were observed and the number infested with psyllid eggs or nymphs recorded. One infested flush of these was collected and examined in the lab under a microscope to count eggs and different instars of D. citri. The number of ACP nymphs per flush was estimated by multiplying the proportion of 10 flush infested by the number counted from the collected flush. ACP density was estimated by counting the adults falling on an 8 1⁄2 × 11 inch white paper sheet (on a clipboard) placed at random under the branches which were then tapped three times. The adult ACP counts were combined over the three sample dates for analysis. The number of larvae and adults of four predatory coccinellids, Curinus coeruleus Mulsant, Olla v-nigrum Mulsant, Harmonia axyridis Pallas and Cycloneda sanguinea (L.) also recorded from the 10 flushes on each tree and the data for all species and stages were combined for analysis. All data were transformed by log(x + 1) and were subjected to ANOVA to evaluate treatment effects on psyllids and the ladybeetles and means were separated using LSD (P = 0.05).