translucens pv. pistaciae NOV09 Anacardiaceae also artificially infect several speciesof has never been found naturally insuchhosts can also infect Poaceae, but onlyartificially, and it lsiida e ahvrof asa newpathovar classified X. translucens The pathogen unproductive up to 10% of the trees. Another serious outbreak occurred recently in2005. the disease occurred with the onset of commercial productionin the mid-late 1990s,or killing rendering 1b). Affected treesfail decline, gradually to produce marketable nutsand eventuallydie.The first outbreak of excessive resinexudates, discolouration of mature xylem(Fig.1a), stunted growth and shoot dieback (Fig. Anacardiaceae X. translucens Spread species in the X. translucens X. translucens host.woody Indicotyledonous thisrespect, The onlynatural host identifiedisPistachio, a Host range group only A iswidespread. distinct,genetically incoexist Australianorchards but to Pistachio. Twogroups, and Aand B, biologically molecular criteria, itsdistinct including pathogenicity basis of biochemicaland severalbiological, press); Marefat Facelli Further Reading translucens Xanthomonas Classification: c Disease Fig. 1. ab This iswork supported by ThePistachio Growers Association (PGA) and Horticulture Australia Limited (HAL) Adelaide. Adelaide, of The University ([email protected]), Scott Eileen and ([email protected]) Giblot-Ducray Danièle Key Contacts: Drs 639-649; Facelli vector hasbeen found. lenticels, or roots wassuccessfulonly rarelyandno been demonstrated: inoculationthrough leaves, through pruning. Nonatural wayof transmission has translucens Typical xylem staining (a) and dieback (b) associated with with associated (b) and (a) dieback staining xylem Typical et al : ., Australasian Plant Pathology (in press); Giblot-Ducray press); (in PlantPathology ., Australasian pv. pv. pistaciae et al Poaceae pv. pv. pathovars, allpathogenic to monocot pv. , unlike ). The diseaseisendemicto Australia andis et al. Pathogen ofthemonth Pathogen ofthemonth Pistachio Dieback D: , C: , O: , F: . (2006) European Journal of Plant Pathology Pathology Plant of Journal European (2006) . pistaciae pistaciae pistaciae (2005) European Journal of Plant Pathology Pathology ofPlant EuropeanJournal (2005) X. translucens nScoePpoeAa c.PooceisC alr(,b n .Slw (c) andA.Salowi b) (a, Taylor C. credits Photo (c). Agar Peptone Sucrose on . X.translucens pv has recentlybeen is uniqueamong seems to beseems to transmitted . pistaciae X. translucens pv. pv. is the causal agent of diebackof Pistachio ( translucens pistaciae It can . Itcan on the the on . efficient control strategies. This needs further investigation to help develop environmental trigger(s) to cause pistachio dieback. X. translucens outbreaks have ledto the hypothesis that spread and symptom expression after the two major Observations ofdownindisease slow unexplained controloptions areBiological beinginvestigated. affected treesand restoringthemproductivity. to has shownsomebenefit severely in managing trees are cut back to secondary or tertiary branches, the spread of the disease. Drasticpruning, where growers are advised to disinfect pruning tools to limit practicesareHygiene of paramount importance and management and Prevention in asymptomaticdetection trees. allowing is themoresensitive, material.RT-PCR optimised for use witha wide range of infected the Pistachio pathogen. These methods havebeen that detectavailable and distinguish the two groups of purposes. arealso and Multiplex RT-PCR PCR slimy colonies (Fig. 1c) that are useful for diagnostic X. translucens Detection X. translucens characterised by trunk and limblesions, 116 112 Systematic and Applied Microbiology (in (in Microbiology andApplied et al.,Systematic , 57-68; Marefat , 57-68; , 155-165. – – pv. pv. November November pv. pistaciae pistaciae pistaciae et al . (2006) Plant Pathology Pathology Plant (2006) . itcavera Pistacia needs biological and/orneeds biological yellow typical produces infection in Pistachio; in Pistachio; infection , 2009 2009 55 X. ,