Surveillance of Citrus Greening Disease in Mandarin Orchard at Jorayal Rural Municipality

Citrus greening disease, which is also referred to as Huanglongbing (HLB), stands as one of the most damaging diseases affecting citrus crop globally, presenting a significant risk to mandarin cultivation in Nepal. This research was carried out to detect the occurrence and evaluate the intensity of citrus greening disease in mandarin orchards located in Jorayal Rural Municipality, Doti district. A total of 72 leaves sample were gathered from four different wards of Jorayal, and two diagnostic methods the iodine-based starch test (scratch method) and the Polymerase Chain Reaction (PCR) test, were used for disease identification.The iodine-starch test results indicated that 6% of the samples produced positive reactions, while PCR analysis verified four positive samples, all originating from fruit-bearing trees older than 10 years in ward number of 6 situated at elevations below 1,200 m. These findings confirm the existence of citrus greening disease in Jorayal’s mandarin orchards, with a higher prevalence at lower altitudes where environmental conditions are conducive to the Asian citrus psyllid vector (Diaphorina citri). The study advocates for the use of iodine-based starch testing as a quick, cost-effective, and dependable field diagnostic method for early detection by farmers.Conclusively, it is recommended that regular monitoring, the use of disease-free planting materials, and enhanced orchard management practices be implemented to prevent further spread and yield loss associated with HLB.