By Subir Bhaumik
BBC News, Calcutta
Oranges are one of Bhutan's most important exports
A virus is wiping out most of the orange crop in Bhutan, causing great concern among the Himalayan country's many orchard owners.
The deadly Huanglongbing (HLB) virus is transmitted by a small fly called a psyllid that thrives on the leaves of the orange trees.
The blight has already caused extensive damage to orange crops in Thailand.
Oranges are the main cash crop in all but four districts of Bhutan and one the country's most important exports.
Last year, exports climbed to a new high, as Bhutan exported 17,208,084 tonnes of oranges to Bangladesh and 1,395,207 tonnes to India.
Orchard owners say they have been receiving record prices for their crop, up to $18 (£12) per box.
"That is why we are so distressed this year," said Pem Dorji, who owns an orchard in Chukha, where one of Bhutan's biggest hydro-electric power projects is located.
"We will lose all our income, we will become beggars."
The psyllid passes on the HLB virus, also known as citrus greening, as it sucks on new leaves of the orange trees.
The virus is transmitted by the psyllid insect and eventually kills the trees
Scientists say the virus infection is so severe that it ultimately kills the whole tree.
It has already wiped out 70% of orange orchards in Punakha, while other orange growing regions like Wangduephodrang, Mongar, Zhemgang and Sarpang are also severely hit.
In Chukha, the entire orange growing region of Baikuenza has been wiped out.
In a circular, the Bhutanese agriculture ministry said the virus could "devastate the whole citrus industry in the country if appropriate measures are not taken soon".
Dr Sangay Duba, of the national plant protection centre, has been quoted by Bhutan's Kuensel newspaper as saying that orchards which used to produce 200 to 300 trucks of oranges every year have barely produced 10 to 15 this year.
"The situation could get worse," he warned.
Scientists say that since most orchard owners in Bhutan are absentee landlords they have paid little attention to plantation management and pest control.
There are 57,000 acres of abandoned or illegal orchards in the country, from where the deadly virus is said to have spread across the orange growing belt of Bhutan.
Concerned at the damage to one of its once most thriving export industries, Bhutan's government has issued an ordinance leading to the creation of an investigation team to control orchard pests.
This team has been given the right of entry into any orange orchard and can fine farmers between 5,000 to 50,000 Ngultrums ($100-$1,000: £68-£680) if they do not implement recommendations about pest control.
The ministry of agriculture has also proposed that illegal orchards whose owners are not traceable should be handed over to landless farmers to be better managed.
Bhutan's national plant protection centre has also developed an "action plan" that involves training and capacity development, quarantine of plants, insect proof nursery and re-plantation in virus-hit areas.