Hawaii island Mayor Billy Kenoi Thursday afternoon signed a bill designed to limit the future planting of genetically modified crops.

“Our community has a deep connection and respect for our land, and we all understand we must protect our island and preserve our precious natural resources,” Kenoi said in a statement.

The bill, approved last month by the Hawaii County Council 6-3, restricts the planting of genetically modified crops to enclosed structures like greenhouses.

Farmers who already grow GMO crops would be exempted from the new ban. That includes the Big Island Dairy and papaya growers, who largely rely on modified varieties that are resistant to the ringspot virus.

In 2008, the county adopted a more limited genetically modified organism bill that banned genetically modified coffee and taro.

Hawaii County is the second county in the state to restrict genetically modified crops. The Kauai County Council voted Nov. 16 to override a veto of a bill requiring large farms to disclose use of genetically modified crops.