The battle against extremism in north-east Syria has moved off the frontline and into the grain fields.

Key points: At least 50,000 hectares of wheat and barley crops have been burnt

At least 50,000 hectares of wheat and barley crops have been burnt Islamic State has claimed responsibility for some of the crop fires

Islamic State has claimed responsibility for some of the crop fires Fourteen people have died in north-east Syria fighting the blazes

Five months after Islamic State (IS) was toppled in a fierce battle over the tiny sliver left of its so-called caliphate, mysterious fires keep breaking out.

Local farmers who were hoping for a good year after a decade of war and drought are now trying to save their crops from arsonists determined to destroy their livelihoods.

The region's Kurdish administration has blamed extremist groups including Islamic State for causing $50 million in damage to this year's wheat and barley harvests.

Agriculture Minister Salman Barudo said multiple fires were lit deliberately each day, with 50,000 hectares destroyed since May.

"After they were defeated on the front line, they wanted to fight us economically," Mr Barudo said.

Mr Barudo said IS had already claimed responsibility for some of the fires.

"It was clear. [Islamic State] announced it on social media. They said, 'we are burning the fields that belong to the infidels, the Kurds,'" he said.

The arson attacks have cost local farmers at least $50 million. ( ABC News: Tom Hancock )

Some Kurds are also convinced the blazes are not solely the work of Islamic State.

Sleeper cells that support Syria's Assad regime and Turkey may have also launched copycat attacks.

It is a bitter blow to the Kurds, who lost 12,000 fighters in the six-year battle to defeat IS.

"They are trying to create a perception that the [Kurdish-led Government] is not able to protect the region here," Mr Barudo said.

Farmers die trying to save their livelihoods

So far, 14 people have died in the fires while they desperately trying to protect their farms.

At least 14 people have died trying to battle the crop fires in Syria. ( ABC News: Tom Hancock )

The ABC witnessed one blaze rip through two fields near the Kurdish city of Qamishli.

Over about 30 minutes, two large fields were completely engulfed by flames.

In hot and windy conditions, locals using sacks and shovels struggled to extinguish the fire, which flared up whenever the winds picked up or the blaze hit a patch of chaff or unharvested wheat.

"This is happening every day, every single day. It's too much for us," one young local man said.

In the village of Amouda, Abdul Aziz lost his 67-year-old father who was burned while trying to dig a firebreak around one crop fire.

"The fire burned his tractor, and he too was burned," Abdul Aziz said.

His father died of his injuries as he was rushed to a hospital.

In a neighbouring village, local woman Jazzaya said she was burned while carrying water through the fields to the local men who were fighting a fire.

She has deep burns on her legs and abdomen.

Jazzaya has already had surgery but has been told she needs more skin grafts, which she cannot afford.

"There are no hospitals here to do the surgery. They told me that I need to go to a private hospital," she said.

This year was meant to be a profitable one for Syrian farmers after a wet winter. ( ABC News: Tom Hancock )

The fires this season are unprecedented and some farmers who spoke to the ABC said the extent of the blazes could be fuelled by an exceptionally wet winter.

Big rains led to much more spring growth: there is simply a lot more grain that is available to burn.

Most of the crops have now been harvested but the fires are continuing, fuelled by several inches of stubble that remains on the ground.

Cooler weather should help them get the blazes under control, but with temperatures still in the 40s, that could be months away.