North Queensland authorities are investigating a case of what seems to be a mass vegetable and fruit sabotage.

Somebody seems to have poisoned an approximate 7 million saplings and 16,000 tomato shrubs at two farms in Bowen, Whitsunday.

Bowen's Supa Seedlings is responsible for supplying seedling s for many of the region's farmers, but now all of its stocked saplings consisting of 4 million tomato seedlings, 2 million capsicum saplings, and melon, eggplant, and pumpkin seedlings are devastated.

The seedling nursery shared the irrigation structure it uses with a nearby hydroponic plantation wherein 16,000 mature tomato shrubs have also wilted.

Dave Miles, detective inspector of the Townsville Police, says evidence shows that it might have been done deliberately in act of sabotage.

"At this stage our investigations suggest that poison has been introduced into the irrigation system; we're still trying to ascertain how that's occurred and what the time frames are around that," the inspector said.

"As a result, the plants have received an application of water which has been mixed with the herbicide which has then led to the death of the plants."

According to farmers' accounts, poisoning sabotage has occurred in the area about four times in the past eight years.

Detective Inspector Miles states that the authorities are filing this case as one of the major incidents.

"There's been a number of reported incidences over the years, and as part of this investigation we'll be going back and looking at those investigations and try to identify if there's any linkages between what we have at this point in time and what occurred on those occasions," he stated.

"We're not ruling out any possibilities at all. It may be as a result of competition, it may be a result of a grudge or vendetta or something, it could be directly related to another incident."

Carl Walker, president of Gumlu Growers Association at Bowen, said the damage will cost the farming region dearly.

"The economic impact on the local community industry is $23 million plus. That's probably being very kind, I know the mayor's been pushing figures of nearly $50 million out there and he could be right," Mr. Walker said.