A mother who was allegedly deliberately run over by a transit van driven by her son has denied spraying him in the face with bleach immediately before the collision.

Martha Drain told a jury at Ipswich Crown Court she had taken a bottle of washing-up liquid with her when she approached the van to talk to her estranged son, Mark Buckland because she was scared and didn't know what to expect from him.

She claimed that Buckland was laughing and had pulled out a sword-like weapon and had stabbed the driver's glass window as he wound it down.

Mrs Drain said she was worried he was going to stab her and she had squirted the contents of the washing-up liquid bottle at him to make him shut the window.

She denied the bottle had contained a corrosive substance such as bleach.

Buckland, 22, of no fixed address, has denied dangerous driving, wounding his mother with intent to cause her grievous bodily harm and a less serious alternative charge of inflicting grievous bodily harm.

The court has heard that Mrs Drain and her son had a "toxic" relationship and there had been a chance meeting between them as they were driving in opposite directions in Tiptree on January 20 last year.

Buckland had indicated that his mother should follow him but when she did he had allegedly repeatedly slammed on his brakes.

Mrs Drain stopped her pick-up truck in Maldon Road, Tiptree, in front of her son's van and went over holding a washing-up liquid bottle.

There was an exchange between the pair during which Mrs Drain claimed her son produced a large knife and waved it in her direction resulting in her squirting some of the contents in the bottle she was holding in his direction.

Phillip Farr, prosecuting, said Buckland denied having a knife and claimed his mother had squirted some sort of noxious liquid into his face which caused a burning sensation.

"The prosecution say that having been squirted with that liquid the defendant in a fit of anger as she was walking away across the road, accelerated and mounted the kerb and ran her over and forced her into a hedge," he said.

"It was a deliberate retaliation designed to hurt her," said Mr Farr.

Mrs Drain later underwent surgery on her leg which was broken in five places.

The trial, which is expected to finish next week, continues.