The restrictions apply to the pesticide ingredients dinotefuran and imidacloprid. Officials say they believe those ingredients killed more than 50,000 bumble bees earlier this year when they were sprayed on trees that have their own natural toxicity.
Bruce Pokarney is a spokesman for the Department of Agriculture. He says the new rules will prevent people from using those two chemicals on linden trees, basswood and other Tilia species with similar toxins.
"It appears there are certain characteristics of this species of tree and certain characteristics of these pesticide products that in combination seem to be fatal to bumblebees," says Pokarney.
The state is sending a letter asking the U.S. Environmental Protection Agency to consider similar rules at the national level.
It is also launching an education campaign for the public and licensed pesticide applicators.
Copyright Oregon Public Broadcasting 2013.