A FARMER spilled thousands of litres of toxic pesticide into an Oxfordshire brook after his trailer toppled over in the middle of the road, a court heard.

Timothy Hook, of Cote, Bampton, denies one count of causing a water discharge activity by causing a poisonous or noxious substance to enter a ditch and brook in West Oxfordshire.

Prosecutors claim that as a result of the accident on May 12 2014 the 37-year old caused the deaths of hundreds of fish, destroying up to half of one species at the centre of the incident.

Richard Banwell, on behalf of the Crown Prosecution Service, outlined the case against against Hook before a jury panel of five women and seven men at the start of his trial at Oxford Crown Court yesterday.

He told jurors that on the day of the incident Hook had been driving his tractor while towing a crop sprayer.

The crop sprayer, which was to be used to treat his agricultural land, contained 3,700 litres of three different pesticides, the court heard, made up of Zephyr, Concert SX and Compitox Plus.

Zephyr is a fungicide while the other two are herbicides.

Travelling on the A415 near Kingston Bagpuize, jurors were told, Hook came on to the roundabout that joins the A420 and it was there that he began to see the crop sprayer swing over.

Mr Banwell said: "While negotiating the roundabout the crop sprayer he was towing overturned, no other vehicles were involved but as a result all the pesticide spilled on to the road and to the highway drains.

"The pesticide spill caused pollution to the Fyfield ditch and to the Marcham Brook."

He said that the pollution poured into the nearby waterways causing the deaths of hundreds of fish, reducing one species near the source 'by a half'.

From Fyfield to Marcham all of the Brown Trout were wiped out, the court heard, representing a 100 per cent mortality rate.

Hook immediately reported the accident, the court heard, and appeared 'very concerned and anxious to help'.

Fire crews and police all attended as did the Environment Agency who launched their own investigation.

On looking into the incident, jurors were told, it was discovered that the pesticide had spilled into a drainage system on the roundabout which took surface water out to Fyfield ditch, which later joined Marcham brook.

An 'interceptor' had been installed as part of the system to catch oil spills from spreading into the nearby water system, the court heard, but the pesticides that had spilled could not be caught by the interceptor, and would quickly pass through it.

Investigators at the EA said they could see an 'opaque substance' and later examined the waterways for dead fish as part of a 'fish mortality survey'.

From observations, the court heard, they estimated that 274 stickleback fish had been killed in the space of 720m of waterways.

There was also about 52kg of Brown Trout the EA said had died as a result and a '100 per cent mortality' for that species between Fyfield ditch and Marcham brook.

Hook denies any wrong-doing and the court heard that while he accepts his pesticides spilled into the road he didn't cause any further discharge.

The trial, expected to last a week, continues.