White was a member of the 2003 World Cup-winning squad

The 34-year-old has agreed to go on stand-by for the competition but will not be part of the 30-man squad.

"I have a young family, and I also have a farm to manage, and I feel I cannot commit to the length of time the squad will be away from home," he said.

"It has been a very difficult decision for me to make."

Interview: England coach Brian Ashton

The Tigers front-rower has bought a considerable amount of land in Devon and plans to increase his farming commitments when his rugby career is over.

White has won 44 caps for England after making his debut in 2000 and was part of the squad that won the World Cup in 2003.

I didn't realise there were going to be issues Phil Vickery on White's decision

He started all three Tests for the 2005 Lions in New Zealand, and joins Northampton winger Ben Cohen in making himself unavailable.

"Obviously it is a massive disappointment because Julian is an exceptionally good tight-head prop," said England coach Brian Ashton.

"I have talked it through with him and I understand why. He has made his mind up."

And England skipper Phil Vickery expressed surprise after hearing that his fellow prop had pulled out.

"I am disappointed myself he's not here because I think he is a great player," he said. "From a tight forward play perspective, there is no doubt Julian is one of the very best in world rugby. It's fact.

"But it is his decision. It is personal to him, and I think you have to respect that.

"I am surprised, personally. It is not something which was known to me. I didn't realise there were going to be issues."

Ashton's 47-man World Cup training squad are currently at their University of Bath base.

And he hinted that the first cut of the party could be made as early as 13 July. The final squad has to be confirmed by 14 August.

606: DEBATE White was sure to be included, the cupboard is beginning to look bare again RM

With White ruled out, Ashton is likely to take four props from a list of skipper Phil Vickery, Bath's Matt Stevens, Andrew Sheridan of Sale, Saracens forward Kevin Yates and Perpignan's Perry Freshwater.

Meanwhile, Ashton has confirmed that Gloucester centre Mike Tindall, who broke his leg in April, has joined up with the squad.

"Mike is in rehab phase," Ashton added on Five Live. "He will be monitored on a daily and weekly basis and I really don't know what the outcome is going to be with him."

And Ashton said it would be a "close call" as to whether Dan Ward-Smith would make the final selection deadline after the Bristol number eight suffered a dislocated kneecap and a ruptured patella in January.

"Dan is making better progress," said Ashton. "He has done selected team training this week and joined in a little bit of contact work on Thursday morning.

"We will see if there is any reaction to that later on and hopefully he can take a fuller part in team training soon."

Wasps flanker Tom Rees did not train this week as a precaution after taking a knock to his knee in the Heineken Cup final.