In October, temperatures were much higher than usual, which led to a loss of about 30% of the crop, with the dates that were harvested of lower quality, he said.
Excessive heat not only dries out the dates but also feeds the growth of an acarid mite that buries itself in the flesh of the date, rendering it inedible.
“If humidity decreases, the number of acarids increases – it is directly proportional,” said Hamadi, pointing to piles of wrinkled dates on the floor of an oasis in Jemna, a town in Kebili.
“No animal would eat this,” he said.
Changes in temperature have also shifted the palms' flowering and pollination periods, causing the male and female plants to fall out of sync.
Farmers pollinate dates manually to maximize production but increasingly there are shortages of pollen because “either the male tree is too advanced, or the other way round,” explained Kadri of the Technical Center for Dates.
As a result of pollination failures, around 10% of this year’s harvest was yellow, hard, and dry.
The deglet nour is much more vulnerable to climate change threats and diseases than other more resistant varieties like the less valuable lalligh, according to Hamadi.
The queen of dates "is very delicate - you need the perfect climate,” he said.
Need to diversify
For Hamadi, the declining fortune of the deglet nour underlines the need to diversify the dates being grown in Tunisia.
Traditional oases contain a variety of date palms as well as other fruit such as pomegranates. But modern plantations, planted since the mid-1980s, are dominated by the deglet nour, which makes up 90-100% of production.
Date farming was encouraged by Tunisia's French colonial government in a bid to settle nomadic communities, with each family given 60 trees, explained Hamadi, whose grandfather was among the recipients.
Later, an exportation drive transformed oases from diverse subsistence ecosystems to intensive agribusiness with rows of just deglet nour date palms, said Imen Louati, a research officer at the Tunisian Economic Observatory.
Tunisia's date exports have shot up over the last 30 years.
According to the UN Food and Agriculture Organization, annual exports were around 15,000 tons in the 1990s and 25,000 tons in 2000.
By 2018, exports had hit 125,000 tons, according to ONAGRI - almost all of them deglet nour.
"It is the variety that sells the best for exportation and so other varieties have disappeared, given that it is more profitable for the farmer,” Louati said.
‘A house without dates’
In Islamic tradition, “people in a house without dates are in a state of hunger.” This is literally true in the Kebili region, where around 50,000 families rely on dates, according to Kadri.
She said damage to the harvest this year has hit local farmers hard.
“Imagine there are people waiting for the dates to marry their sons, for the studies of their children, to go to hospital,” she said.
Some unlucky farmers, who rely entirely on the date harvest for an income, lost the whole of their crop this year to mites, she said.
“They have a harvest with zero product, zero profit. They just harvest to let the tree start again for next season,” she said.
Date vendor Ghiloufi’s market stall in Kebili has a third fewer top quality dates this year than previously, he said.
One solution is to sell dry but still edible dates – termed “majbouda” - to exporters who have conditioning centers to better hydrate and package them before they are sold abroad.
But Hamadi and his team at the Institute for Dry Regions are looking at other ideas, including using the fiber from non-pollinated dates - bitter but rich in antioxidants – in juices and cakes.
Farmers also need to be encouraged to plant more than deglet nour dates, he said.
“We need to convince farmers that it is not just important to earn money, but also to protect your oasis,” Hamadi said.
He understands the challenge, he said: His own family's date trees are still 99% deglet nour.