In a first for Australia, synthetic caffeine is being trialed as a way to kill snails that are invading crops, particularly in South Australia and Victoria.

The South Australian No Till Farmers Association is in its second year of the trial.

Research and development manager Greg Butler says caffeine is an option for farmers because other methods can't be used later in the season.

"When you have a crop up late in the season and snails are running rife, you can't bash your crop down, it doesn't make economic sense, and you can't burn it because it is wet and green, so we've got a gap in that system," he said.

"And I guess having a foliar spray with caffeine in it is an opportunity to maybe plug that gap with something that is fairly food safe."