Results on attempts in management of HLB under small scale in Vietnam and initiation in screening for HLB tolerant from varieties/clones belonging to Rutaceae

In the Mekong Delta, Vietnam, Citrus Huanglongbing (HLB) was officially announced in 1994 and its causal organism was described by Bove and Garnier in 1995 to be Candidatus Liberibacter asiaticus. Throughout the years, intensive works have been carried out for HLB control under small scale orchards and the achievements are discussed, the model for effective control of HLB under small scale which could elongate the life cycle of citrus tree for better and longer harvesting. In addition, there were 130 rutaceae related accessions had been collected and screened for HLB tolerance; the results revealed that the serverity of HLB infection was less on Hanh/Tac/Quat (Citrus microcarpa) and Long Co co pummelo (Citrus maxima) than that on orange and mandarin. The wild Rutaceae species/clones such as Quyt Dang, Quyt rung, Cam rung, Buoi Rung, Buoi Dang, Buoi Bung, Mac Run, Mac Mat, Can Thang, Quach, Nguyet Que, Kim quit, Truc, Com Ruou, Dau dau ba la, Ca ri, Da tu bien and Gioi Lom were symptomless under transmission conditions and had a negative reaction by PCR tests. In a molecular study, 38 primers have been designed and used for screening of HLB tolerance capacity of 49 varieties/clones belonging to Rutaceae. The preliminary results shown that the tolerant varieties was grouped into Group D, which somehow matched with the tolerant group screened under screenhouse conditions.