Syrian agriculture has been shattered by a raging 22-month conflict that has left more than 60,000 people dead, the UN Food and Agriculture Organisation said on Wednesday.
The FAO said in a statement the livelihoods of about half of the country's population were threatened as a result.
"Twenty-two months of conflict has left Syria's agricultural sector in tatters with cereal, fruit and vegetable production dropping for some by half and massive destruction of irrigation and other infrastructure," it said.
"Destruction of infrastructure in all sectors is massive," said Dominique Burgeon, FAO's Emergency and Rehabilitation Division director after a five-day visit to both regime- and rebel-controlled areas.
The UN says that about 80 percent of 10 million Syrians -- about 46 percent of the population -- derive their livelihoods from agriculture.
"The mission was struck by the plight of the Syrian people whose capacity to cope is dramatically eroded by 22 months of crisis," said Burgeon.
The FAO said wheat and barley production was halved last year, going from 4 to 4.5 million tonnes in normal years to less than 2 million tonnes.
"Only 45 percent of the farmers were able to fully harvest their cereal crops while 14 percent reported they could not harvest due to insecurity and lack of fuel," the FAO said.
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It highlighted a lack of irrigation because of damage to irrigation canals and a lack of fuel, while the movement of livestock to grazing areas was thwarted.
The survival of livestock, said the FAO, "is compromised by the lack of animal feed and veterinary drugs, the importation of which is hampered by sanctions."
Poultry farms have also been destroyed in the central provinces of Homs and Hama, and in Idlib in the northwest.
The FAO said agriculture workers need urgent assistance to be able to cope with the effects of the spiralling crisis.
"It is clear from discussions... that security conditions permitting, agriculture has a huge role to play in helping people to stay on their land and generate income to cope with their most urgent needs," said Burgeon.
"They, however, need urgent agricultural support in terms of seeds, fertilisers, animal feed, veterinary drugs, poultry and rehabilitation of irrigation infrastructure."
Several flashpoints in Syria's conflict, chiefly Damascus and Aleppo in the north, have been struck by a severe bread shortage and a lack of fuel used for cooking, heating and transportation.