Report of diplodia stem rot disease in SoE-Mollo-Citrus in Timor Tengah Selatan Regency, East Nusa Tenggara

Abstract

SoE-Mollo-Citrus is prominent in East Nusa Tenggara. However, a consortium of pathogens infects citrus plants, causing symptoms of broken stems with peeled bark associated with or without gum production. These symptoms could be caused by Lasiodiplodia sp. or Phytophthora sp. Considering the importance of SoE-Mollo-Citrus for society and the Government, actual and accurate information is profound regarding the presence of primary diseases that threaten it. This research aimed to determine disease intensity in central SoE-Mollo-Citrus production villages and to identify pathogens isolated from stem rot symptoms. Stratified purposive sampling method was applied to select seven Districts and ten Villages having large SoE-Mollo-Citrus populations. In each village, one orchard was randomly chosen for observation. SoE-Mollo-Citrus showing symptom of wet and dry diplodia were present in every observation village. The incidence and severity of the disease ranged from 30% in Mnelalete village to 75% in Oelbubuk village and between 21% in Tubuhue village to 51% in Oelbubuk village, respectively. Seventy percent of the collected isolates were pathogenic. Morphological and molecular identification using Primers ITS2 and ITS5 confirmed that the stem rot pathogen was Lasiodiplodia theobromae Pat. Syn. Botryodiplodia theobromae. Good agricultural practices are mandatory so this disease does not harm citrus production.