Drier weather this summer has allowed the number of rabbits to get beyond levels that can be effectively controlled by shooting.
But the Otago Regional Council is also warning farmers dealing with increased rabbit numbers not to try to re-release the RCD virus - as has been widely rumoured - because it could "do more harm than good".
Regional services group manager Jeff Donaldson said rabbit numbers had reached the point, especially in Upper Clutha, that secondary control, such as night shooting, helicopter shooting, or gun and dog, were no longer effective.
This was due to the fine weather allowing rabbits to survive and continue to breed.
"Throughout Central Otago they are breeding very well due to the drier climate."
Although many farmers were doing a good job controlling rabbits, there were "a number" that would need assistance to choose the right method, Mr Donaldson said.
The greatest concern was that one property owner's failure to carry out rabbit control did not impact on the neighbours' success and did not degrade the land.
However, farmers trying to re-release the RCD virus were "wasting their time" as it would weaken the virus already present, especially given the immunity in the population, Mr Donaldson said.
Rumours abounded of people re-releasing the virus but property owners should not "fiddle with it" and instead leave the virus already present to do its work naturally, he said.
"It can continue to be helpful, as long as people keep their rabbit numbers down."
However, when rabbit numbers were high, as they were this season, it "could not manage the problem for us".
The council was inspecting properties around the region to see if their rabbit management plans were controlling numbers.
Farmers were required to submit management plans outlining ways they would keep rabbit numbers down to the required level for council approval if their control methods had failed.
Those plans were audited every 12 months and if the farmer had failed to comply with the plan they would be required to alter it, or if they did not agree, would be issued with a "notice of direction" to undertake the work in a specified time.
Some already inspected would be receiving notice of directions to undertake poisoning work using either Pindone or 1080.
As a result, Regional Services had indicated to growers it would need more carrots to use as bait this winter.
Although the final amount would not be known until inspections were finished, Mr Donaldson estimated a further 500 tonnes, over the 1500 tonnes used last year, would be needed.
Rabbiter Ray Moffat, who works on Central Otago properties, said some properties in the area were really good as far as rabbit numbers were concerned, while others were "really bad".
"It's a real mixed bag, but it hasn't been as bad an increase as it was last year."
Those places with high rabbit numbers had mostly been relying on one method of control and not doing follow-up work to keep on top of numbers, he said.
He recommended rabbit-proof fencing and clearing scrub to assist in keeping numbers down.
"It's not a problem that will go away quickly."
Given that farmers were in a better financial position thanks to increased wool and meat prices, they could afford to spend more on control, he said.