A team of detectives is looking for those responsible for the poisoning at a Bowen nursery late last month.
They'll also look at possible links with similar crimes in recent years.
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In the latest case, about seven million plants, including about four million tomato seedlings, were lost. Other affected crops include capsicums, melons and eggplants.
Growers say tomato prices could double or triple within months.
Liberal National Party Member (LNP) for Burdekin Rosemary Menkens says at least 30 local Bowen farms will lose a majority, if not all, of their income for a whole season.
"But it is not just the growers who have been affected, with contract workers, from pickers, packers and truck drivers all losing work because there will be no fruit or vegetables to pick."
She said it has been estimated that $6.5 million dollars worth of wages will be lost in the region between now and September.
"The cost to the community is huge - it will be a very quiet Christmas in Bowen this year.
Ms Menkens called for more police resources to be made available for the investigation.
Whitsunday Mayor Mike Brunker on Thursday asked the government to post a $200,000 reward to help find those responsible, saying it's the fourth time in a decade that crops have been sabotaged.
Police Minister Neil Roberts said the request was being considered.
