About seven million plants, including about four million tomato seedlings, have been lost after they were poisoned with a herbicide at a Bowen nursery last month.
Other affected crops include capsicum, melons and eggplant.
Bowen Growers Association spokeswoman Denise Kreymborg said the Bowen region was the largest producer of winter vegetables and the poisoning would affect about 30 to 40 growers in the area.
Growers will continue harvesting their established crops in the next two months, but prices are expected to spike around September when produce from the seedlings would have been on the market.
“You can expect prices to double or even triple, we don’t know for sure,” Ms Kreymborg told AAP.
“There’s still going to be tomatoes, capsicum, melons, zucchinis and eggplants grown in this area, just not as much.”
Whitsunday Mayor Mike Brunker said it was the fourth time crops had been sabotaged in the region in the past decade.
He called on police to offer a major reward for information about the crime.
“We just need someone to come forward who knows the grub who has done this,” he said.
Townsville Police Acting Inspector Dave Miles said 12 detectives were working on the case and would investigate possible links with the previous poisonings.
He said a range of possible motives were being considered.
“It could be a grudge, it could be competition based, it could be the result of time-established market share, or it could be an act of vandalism by a couple of young hoons – we can’t rule that out either,” he told AAP.
The price spike will bring back memories of Cyclone Larry, which devastated most of Australia’s banana crop and resulted in the price of the fruit spiralling beyond $10 a kilogram.
Ms Kreymborg said the poisoning was on a much larger scale than previous incidents.
She said the loss of revenue would be hard for growers after a tough year last year and weak performance in recent months.
“There could quite possibly be growers who are affected in that way,” she said.
“They’re not breaking even right now and they probably won’t be next month either, and then in September they won’t be making any money at all.”
She called on consumers to support growers by buying local produce.
“We really need consumers to go and ask where the produce comes from and to buy even one extra tomato to support the industry now so it doesn’t fall over.