SALEM, Ore. (AP) – A pesticide that caused the death of more than 2,000 trees in Central Oregon is facing new regulations despite objections from agrichemical giant Bayer AG.

The Oregon Department of Agriculture said Thursday that it will immediately begin severely restricting the use of herbicides containing the chemical aminocyclopyrachlor, or ACP. Regulators found ACP was the main ingredient that killed more than a thousand trees near Sisters from 2013 to 2015.

This makes Oregon the first state to limit the herbicide on a statewide basis.

Regulations were meant to go into effect in March but were postponed after the chemical company Bayer filed for a delay.

The rule would prohibit using the chemical in wildlife management areas and make permanent current temporary restrictions on use in right-of-ways for roads, highways, railroad tracks, bike paths and more.

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