1a. Objectives (from AD-416):
Identify optimal blends and application methods for semiochemical-based products to control citrus leafminer and citrus canker disease.
1b. Approach (from AD-416):
Replicated, multi-locational field trials in commercial citrus groves will identify the optimal mating disruption formulations and best application rate, coverage pattern and frequency for control of citrus leafminer.
3. Progress Report:
This project is directly related to Objective 1, Develop semiochemical-based control methods for citrus pests, particularly Asian citrus psyllid (ACP). During summer 2012, we concluded a split-plot trial to test SPLAT CLM applications in winter when citrus leafminer populations are low and in spring when populations typically increase. Winter application had no effect on trap catch disruption in spring and summer. Spring application reduced trap catch by about 50 percent during the first 5 weeks post-application, but not thereafter. Damage by citrus leafminer did not differ among treatments. Validation trials concluded during summer at 3 sites confirmed similar performance. A third trial with SPLAT CLM showed no difference in disruption of trap catch between plots treated with triene (current formulation) and a 3:1 triene:diene blend of the two major pheromone components. During summer and fall 2012, we initiated a small plot trial that demonstrated superior trap catch disruption with rubber dispensers (>90 percent disruption for 22 weeks) loaded with triene or blend pheromone. A second trial consisting of larger plots also demonstrated excellent trap catch disruption with rubber dispensers (>90 percent disruption for 30 weeks) loaded with blend. Two large-scale field validation trials demonstrated similar or better performance using rubber dispensers. During spring 2013, we initiated a second split-plot trial to test the value of rubber dispensers loaded with triene applied in winter and spring. Trap catch disruption has remained strong (>90 percent) in treated plots through 18 weeks. Damage caused by citrus leafminer has not differed in treated and untreated plots. Two large scale validation trials (100 acres each) using rubber dispensers are ongoing. In both trials, trap catch disruption was >95% for 30 weeks. We tested a revised rubber dispenser that proved inferior compared with the original dispensers. We initiated two studies of flight and colonization capability of leafminer. Males traveled up to 1200 m to find pheromone-baited traps; females colonized potted sentinel trees 1200 m from a known source of infestation within 6 weeks. An ongoing trial tests attraction of citrus leafminer and a congeneric leafminer (Phyllocnistis insignis) to pheromone blends that contain two or three sex pheromone components to determine the effect of mating disruption on nontarget species.