Citrus, mainly mandarin, is almost exclusively grown as a cash crop. It is the most important fruit crop in Bhutan (33,470 MT of mandarins produced in 2013), with most exported (75% in 2013).
Citrus is grown in 16 dzongkhags with major areas located in the subtropical southern regions. Fruit from higher altitudes (> 1,300 m) get problems of being sour, but still fetch good prices (~Nu. 150/kg) in the domestic market late in the season.
There has been considerable research and development investment directed at helping improve horticultural and plant protection practices for citrus within Bhutan over the past few decades. Much of this has come from the Australian and Japanese governments.
Citrus is prone to a wide range of insect pests and diseases, as well as a parasitic plant. Trees are particularly vulnerable to foliage pests when they are young and actively growing, such as in nurseries. Most pests are relatively minor or can be managed through regular monitoring and good orchard management. The main exceptions are the Chinese fruit fly, Citrus shield bug, Huanglongbing (HLB) and powdery mildew.
Chinese fruit fly and the citrus shield bug can both cause significant losses through premature fruit drop every year across the country. Chinese fruit fly especially remains difficult to manage.
Huanglongbing was present around Phuentsholing by at least 1992 but has since spread extensively. The disease causes orchard decline and death, especially below about 1500 m asl, It will continue to threaten the citrus industry in Bhutan until management tools can be found and implemented. Severe outbreaks of citrus powdery mildew can cause tree die-back. Outbreaks can be quite serious in many areas.
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