A review on economic impact of citrus greening on Mandarin production in Nepal

Abstract

Citrus greening is found to be one of the most devastating diseases associated with three species of Candidatus liberibacter. The transmission takes place by Asian citrus psyllid and causes heavy yield loss in all type of citrus fruits especially on mandarin fruits. Destruction of many well established mandarin orchards by greening can be seen profusely in Nepal. It has reduced the mandarin productivity significantly on about 55 mandarin producing districts of Nepal. Yield was declined to around 9 Mt/ha from 12mt/ha in the course of only four years which might have gone very low if no proper control measures has been applied. Greening does not have any specific remedial therapy but application of various integrated management technologies can control the disease. Symptoms of greening can be seen on canopy as mottled leaves, on root system as reduced fibrous root, on fruits as lower juice quality and can be detected from external appearance of trees but the confirmation should be done through various laboratory tests. The disease had reached to almost all major mandarin producing districts and had affected farmers not only by reducing the production but also by decreasing fruit quality and increasing the management cost of mandarin. Greening can be controlled only by managing plants properly from seedling stage to fruiting period. High quality planting materials, application of essential fertilizers, nutrients and hormones, proper training and pruning, regular irrigation, pest management etc can reduce the effect of greening on mandarin. Citrus-Guava inter-cropping has also been found to give best result in vector reduction.