The sweet, round mandarins that hang from the trees on the hilly terrain of the district usually bring much joy to the farmers of the region.

The juicy, citrus fruits are harvested once a year as an early winter fruit in the region where farmers hold ladders up to the trees that grow up to six feet in height and the branches are thinned by hand or knives.

But an unlikely scene is puzzling farmers this year, as fruits are dropping off from the branches even before ripening, leading to huge loss. The farmers can attribute this strange phenomenon to a spike in temperature and lack of fog compared to last few years.

Anisur Rahman, assistant meteorologist of Sreemangal weather monitoring office, said the average temperature recorded between October 1 and October 11 last year was 23.6 degrees Celsius, but it rose to 24 degrees in the same time this year.

“I am incurring huge loss as the fruits are falling off even before maturing,” said Abdus Sahid, a resident mandarin farmer of Suknachhera village under Juri upazila. He cultivated mandarins on an acre of land and sold his produce at Tk 55,000 last season. However, sales dropped to Tk 30,000 this season.

Farid Uddin, another farmer of Kochurgul village in Juri, said the fruits are not maturing to its typical bright orange colour. “It is a bit faded colour and bitter in taste, lacking its distinctive sweetness.”

Growers are apprehensive about recovering their investments as they have already spent on fertilisers, fencing to prevent theft and wages on workers to make sure the plants are deweeded and free of insects.

Azir Uddin, a mandarin trader from Suknachhera, has been wholesaling the fruits from the foothills of this region for last 25 years.

Mandarin farming is usually more profitable than many other crops. The nutritious snack food is popular with consumers at both home and abroad since these are easy to peel, he added.

“I sold mandarins for Tk 12-15 a piece last year. But this year, I sold a piece for only Tk 7-9 for the poor quality.”

Increased rainfall also had a part to play in the disorder, as the trees have become more prone to insect attacks.

According to agriculture officials, the upazila has 415 mandarin orchards across its six unions, occupying about 93 hectares of hilly landscape. Total production in the upazila rose from 145 tonnes in 2014-15 to 300 tonnes in 2015-16.

However, the yield might drop this year, they added.

Mahfuz Shakil from Kulaura has recently bought two dozens of mandarins from local plantation. At first, he was excited to see the growers collect the mandarins in baskets and placing them in cases, ready for transportation. But later he could not consume the immature, bitter fruits even after two weeks.

Debol Sarkar, agricultural officer in Juri upazila, said mandarins blossom well in the shade and the plantations are suffering for high temperatures. “The fruits seem to be shrivelling up for direct sunlight.”

Dr Md Sharaf Uddin, chairman of agro forestry and environmental science department of Sylhet Agricultural University, said the reason behind apathy among the farmers towards mandarin cultivation is unfavourable weather condition.