But as the virus was only set to kill 40% of rabbits, he needed something more effective, he said.
"If [the virus] killed 95% of rabbits we may have changed our minds [on 1080]."
He said the anti-1080 activists should have "nothing to worry about" as "1080 breaks down when it hits the ground and can they come up with an alternative? It's either rabbits or us."
Despite Mr Leask not having dropped 1080 for several decades, his contractor said the practice had been common "since the 1950s".
The contractor, who wished to remain anonymous, is carrying out work from July-September to kill rabbits on the Booth Rd farm and Ida Valley Station using 1080 poison.
The poison was only used for a short period during winter, when rabbits stopped eating grass and turned to carrots, he said.
His company dropped 1080 on five to six Central Otago farms each winter, and four other companies in the area did the same.
"The farmers, they've been doing this forever pretty much, doing blocks every year to keep on top of the rabbits. It's something they need to do to maintain their farming practices."
The contractor said the amount of 1080 used in the rabbit drops was "at its lowest dosage" at 0.2%, compared with 0.8% for drops to kill possums.
While controversial, the use of 1080 was vital for farmers, some of whom spent at least $100,000 annually on rabbit control, the contractor said.
Otago Regional Council director of environmental monitoring and operations Scott MacLean said the operation was not part of a council programme but it was not concerned by the use of the poison.
"It is every land occupier's responsibility to control pests on their land and 1080 is commonly used to achieve this ... 1080 is an effective toxin in rabbit control. It has been used for many years and is considered an important tool in the pest-control toolbox."
