INDIANAPOLIS — Indiana's wildlife agency has issued an emergency rule banning walnut products from nine western states and Tennessee from being shipped into Indiana.

The rule took effect Monday and is intended to prevent a tree disease that afflicts black walnut trees and other walnut species, including butternut, from reaching Indiana.

Officials with the state Department of Natural Resources say Thousand Cankers Disease is a major threat to the state's black walnut trees.

The new rule applies to walnut products from Arizona, California, Colorado, Idaho, Nevada, New Mexico, Oregon, Tennessee, Utah and Washington.

It bans walnut nursery stock and a variety of unprocessed products such as firewood and mulch from being shipped into Indiana.