FOLIAR INSECTICIDES AGAINST ASIAN CITRUS PSYLLID AND CITRUS LEAFMINER IN ORANGES, 2009

Asian citrus psyllid (ACP) is the vector of the bacterium Candidatus Liberibacter asiaticus causal organism of citrus greening disease or “Huanglongbing. Feeding damage from citrus leafminer larvae (CLM) facilitates the spread of citrus canker caused by Xanthomonas axonopodis pv. citri. Effective control measures are thus needed for these two exotic pests of Florida citrus. The experimental block at the Southwest Florida Research and Education Center (SWFREC), Immokalee, Florida consisted of 14-yr-old sweet orange Citrus sinensis (L) Osbeck ‘Valencia’ trees planted on double-row raised beds at a density of 132 trees/acre. Trees were irrigated by micro-sprinklers, subjected to conventional cultural practices, and pruned 2 weeks prior to treatment with a hand held hedger to induce new shoots and encourage psyllid infestation. Nine treatments and an untreated check were randomly distributed across 4 replicates in 19 rows that included a buffer row after every treated row. Each replicate contained 10 plots of 5 plants distributed across 10 treated rows. Treatments were applied to both bed and swale sides of the trees on 21 Sept 2009 using a Durand Wayland 3P-10C-32 air blast speed sprayer operating at 1400 RPM with 5 stainless steel T-Jet # 5 nozzles per side and applying 120 gpa. Three central trees per plot were included in post treatment evaluations made on 24 Sept, and 1, 8, 15, and 22 Oct. Nine randomly selected shoots per plot were collected and examined under a stereomicroscope in the laboratory to count psyllid nymphs. Fresh mines made by leafminer larvae were also counted on 5 leaves per shoot on 1 Oct. Adult psyllid density was estimated from three central trees in each 5-tree plot by counting the insects falling on a clipboard covered with an 8 1⁄2 × 11 inch laminated white sheet placed under randomly chosen branches which were then tapped 3 times with the PVC pipe to make a count for one tap sample. Four tap samples were conducted per tree. Data were subjected to ANOVA to evaluate treatment effects on ACP and treatment means separated using LSD contingent on a significant treatment effect (P = 0.05).