LIKE a simmering ragout coming on the boil, the investigation into North Queensland's attack of the tomato killers has entered a new phase.

Yesterday police raided a farm and two homes on the outskirts of Bowen, seizing computer equipment and chemical samples.

No arrests were made but the lead investigator, Detective Senior Sergeant David Miles, said police were progressing well with their investigations into the June 20 attack, which destroyed 7 million seedlings, including 4 million tomato plants.

He said police had acted on ''information that links certain entities to involvement in the crop poisoning'' and did not rule out more raids. One of the victims of the poisoning, Leslie ''Toss'' Eisemann, of Supa Seedlings, estimated his loss at between $1.2 million and $1.4 million, including the cost of clearing the land and upgrading security.

After initial speculation pointed to rival tomato-growing regions in Queensland and even Western Australia, Mr Eisemann said he was not surprised the investigation was centred on Bowen. ''Local knowledge is probably an advantage if you want to do this sort of thing.''

Mr Eisemann declined to comment on yesterday's raids but he said the attacker, once convicted, should receive the maximum penalty. The state government has also promised a reward of up to $200,000.

Another victim, Jamie Jurgens, said the growers who salvaged some of their crop would power on for another six weeks, when the season will end. ''Everyone's sort of moved on and doing what we do every day.''

The poisoning led to predictions that tomato prices would double or triple late this month or next month.