Sydney ? When the enemy reached Australia’s largest state last year, the Kimberley Toad Busters knew the battle was on. But they didn’t expect that officialdom might strip them of their most effective weapon.

The enemy? The cane toad. The weapon? Plastic bags full of carbon dioxide — long considered the animal-friendly alternative to whacking the creatures with golf clubs or cricket bats.

But Western Australia’s Department of Environment and Conservation isn’t so sure that euthanizing Bufo marinus with carbon dioxide is the kindest way to go, and says further tests are needed.

Should the tests prove the toads are suffering, the carbon dioxide option could be banned across Western Australia. And that, the Toad Busters fear, would make the war against cane toads virtually unwinnable.