The EPA has reversed course in its effort to restrict a widely used, insect-controlling pesticide, backpedaling on one of the Obama administration’s key initiatives to lower pesticide exposure.

The Environmental Protection Agency will deny a decade-old petition from environmental groups to revoke all uses, called “tolerances,” of chlorpyrifos on food, EPA Administrator Scott Pruitt announced March 29. The insecticide is an important crop protection tool for fruit, vegetable and row crop growers.

“We need to provide regulatory certainty to the...