EFFECT OF SPRAY VOLUME AND SPRAYER TYPE ON EFFICACY OF INSECTICIDES FOR CONTROL OF ASIAN CITRUS PSYLLID AND CITRUS LEAFMINER ON ORANGES: 2010

ACP and CLM are two economically important pests of Florida citrus due in large part to their role in the spread of greening disease or “huanglongbing” and citrus canker caused by Xanthomonas axonopodis pv. Citri respectively. We evaluated the efficacy of Movento in total spray volume 5, 10, 40 and 120 gpa compared to three other standard treatments. The two lower volume rates were applied with a Proptec rotary atomizer sprayer by varying speed of the peristaltic pump. The two higher volume rates were applied with a Durand Wayland 3P-10C-32 air blast speed sprayer operating at 2.3 mph and 200 psi with four Albuz ATR 80 nozzles per side delivering 40 gpa (white nozzles) and 120 gpa (green nozzles). The experimental block at the Southwest Florida Research and Education Center, Immokalee, Florida consisted of 15-yr-old sweet orange ‘Valencia’ trees planted on double-row raised beds at a density of 132 trees/acre. Trees were irrigated by micro-sprinklers and subjected to conventional cultural practices. Trees were pruned 3 wk prior to application to encourage growth of new shoots essential for reproduction of ACP and CLM. Eight treatment plots of 10 trees were randomly distributed across each of the 4 replicates, one per row separated by a buffer row. Treatments were applied on 30 Sep 2010 and evaluations made at 4, 11, 18 and 25 DAT. Fifteen randomly selected shoots per plot were collected and examined under a stereoscopic microscope in the laboratory to count ACP nymphs. Five of the 15 shoots were examined under the microscope to count CLM larvae and empty mines on three fully expanded leaves per shoot. Density of ACP adults was estimated from five trees in each plot by counting those falling on a white clipboard placed under randomly chosen branches which were then struck 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 and means separated using LSD (P = 0.05) are presented.