title: Vector control and foliar nutrition to maintain economic sustainability of bearing citrus in Florida groves affected by huanglongbing.
abstract: BACKGROUND
  Huanglongbing (HLB) or citrus greening is a bacterial disease vectored by the Asian citrus psyllid (ACP) causing tree decline, and yield loss. Vector control and foliar nutrition are used in Florida to slow the spread of HLB and mitigate debilitating effects of the disease. A four year replicated field study was initiated February 2008 in a 5.2-ha commercial block of young 'Valencia' orange trees employing a factorial design to evaluate individual and compound effects of vector management and foliar nutrition. Insecticides were sprayed during tree dormancy and when psyllid populations exceeded a nominal threshold. A mixture consisting primarily of micro- and macro-nutrients was applied three times a year corresponding to the principal foliar flushes.
  
  
  RESULTS
  Differences in ACP numbers from five- to 13-fold were maintained in insecticide treated and untreated plots. Incidence of HLB estimated by polymerase chain reaction (PCR), rose from 30% at the beginning of the study to 95% in only 18 months. Highest yields all four years were seen from trees receiving both foliar nutrition and vector control. Production for these trees in the fourth year was close to the pre-HLB regional average for 10 year old 'Valencia' on 'Swingle'. Nevertheless, at current juice prices, the extra revenue generated from the combined insecticide and nutritional treatment did not cover the added treatment costs.
  
  
  CONCLUSIONS
  This experiment demonstrated that vector control, especially when combined with enhanced foliar nutrition, could significantly increase yields in a citrus orchard with high incidence of HLB. Economic thresholds for both insecticide and nutrient applications are needed under different market and environmental conditions.
authors.affiliation: Southwest Florida Research and Education Center, University of Florida/IFAS, Immokalee, FL, USA.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Stansly
authors.forename: H Alejandro
authors.initials: HA
authors.lastname: Arevalo
authors.forename: Jawwad A
authors.initials: JA
authors.lastname: Qureshi
authors.forename: Moneen M
authors.initials: MM
authors.lastname: Jones
authors.forename: Katherine
authors.initials: K
authors.lastname: Hendricks
authors.forename: Pamela D
authors.initials: PD
authors.lastname: Roberts
authors.forename: Fritz M
authors.initials: FM
authors.lastname: Roka
mesh_terms: D000383:Agriculture / Q000191:economics; D000818:Animals; D002957:Citrus / Q000191:economics / Q000254:growth & development / Q000382:microbiology*; D005308:Fertilizers / Q000032:analysis; D005431:Florida; D005638:Fruit / Q000191:economics / Q000254:growth & development / Q000382:microbiology; D006430:Hemiptera / Q000187:drug effects / Q000382:microbiology*; D007300:Insect Control / Q000191:economics; D007303:Insect Vectors / Q000187:drug effects / Q000382:microbiology*; D010935:Plant Diseases / Q000191:economics / Q000382:microbiology*; D012230:Rhizobiaceae / Q000502:physiology
chemical_list: D005308:Fertilizers