Cultural Practices to Prolong productive Life of HLB Infected Trees. Through the summer of 2009 trees receiving the nutritional/SAR trees were vigorous and green with only normal HLB symptoms typical of HLB infected trees. This fall of 2009 at our 100% infected trial site we have observed numerous visual HLB symptoms in multiple sectors of the trees. Although our other two sites with lower infection rates of 50% and 15-20% had increased visual symptoms of HLB this fall and winter typical of greening trees, the symptomatic leaves were not as abundant as in the more infected trees. Fruit color break from green to yellow in Valencia oranges began early (late September) at the site with 100% infected trees and was not observed at the two other sites where fruit remained green as typical in uninfected trees. Fruit drop has been observed this fall only in the 100% infected trial. Data collected show treatments with the complete Maury Boyd cocktail, with or without hydrogen peroxide, and the foliar feed macronutrients in a typical range of 2 to 5% fruit drop. The other treatments ranged from 8 to 17% fruit drop. No abnormal coloring of fruit or fruit drop has been recorded in sites with 40-50% or 15-20% HLB infection. Evaluation of Systemic Acquired Resistance Inducers Combined with Psyllid Control to Manage Greening infected Groves We are monitoring Asian citrus psyllid (ACP) populations and Can. Libericacter asiaticus (CLas) titer in plants and psyllids to evaluate main effects and interactions from a 2×2 factorial experiment with with 4 replications and 4 treatments: (1,2) (micronutrients + systemic acquired resistance inducers (Micro+SAR) with and without insecticidal control (3) insecticidal control alone, and (4) untreated. The trial is being conducted on a 12-acre commercial block of now 7-year-old ‘Valencia’ oranges on ‘Swingle’ rootstock that was held back by defoliation for canker control in 2006. Adult ACP populations have been maintained three times lower on average and up to 50 times lower on occasions in insecticide-treated plots compared to untreated plots throughout both years of the experiment. Insecticides have been applied 6 times during that period, either as a single scheduled dormant spray in winter or when adult populations exceeded a threshold of 0.5 per biweekly ‘tap’ sample made by striking a randomly selected limb while holding a laminated sheet underneath to catch fallen psyllids. ACP adults and nymphs have been collected 4 times since Nov 2008 for PCR analysis along with a leaf sample from the most symptomatic branch of every 5th tree. Insect samples were sent to our collaborators at USDA Riverside CA for analysis and plant tissue samples were processed at the PCR laboratory at SWFREC. In November 2008 and April 2009, 34% of the plants were positive for HLB over all treatments using a cutoff Ct value of 36. Incidence of HLB jumped to 85 – 100% positive in Aug. 2009. However, the two treatments employing insecticidal control had significantly higher Ct values (28.5’0.7) than the two non-insecticide treatments (26.4’0.6) indicating lower CLas titer in plants protected by insecticides. All fruit was harvested in Mar 2009 and yield was assessed by plot. Despite the high percentage of infected trees, those receiving both insecticidal and Micro+SAR produced 1.32’0.15 boxes per tree of fruit, a 30+% increase over 0.95 to 0.99 boxes per tree from the other 3 treatments. An analysis by the CREC pilot plant in Lake Alfred found no significant treatment effects on fruit or juice quality. These results could be interpreted to mean that the Micro+SAR package is capable of staving off negative impacts of HLB if CLas titer can be maintained below some threshold level through psyllid management. However, we will not begin to feel comfortable with this conclusion until we see similar encouraging results from the spring 2010 harvest.