May 9, 2025 (Sacramento, CA) — The California Department of Pesticide Regulation today announced an enforcement action against an Idaho company, Keystone Pest Solutions, for alleged violations of California state law governing the sale of restricted material pesticides in the state.
The licensing discipline that DPR has initiated accuses the company of selling California restricted material pesticides to purchasers that did not have the legally required permits to purchase them. According to the accusation, Keystone violated these rules 159 times over a four-year period ending in July 2024, representing approximately 80 percent of the company’s California sales of California restricted material pesticides during that timeframe.
“Pesticides are strictly regulated so we can manage pests safely,” said Ken Everett, Deputy Director of DPR’s Enforcement Division. “It is especially critical that businesses adhere strictly to all the requirements applicable to restricted materials. We are holding Keystone accountable for putting people and the environment at risk.”
Restricted material pesticides are a category of pesticides subject to California’s strictest regulations, including requirements on where they can be used, who can use them and how they can be used. California law requires businesses delivering or selling restricted material pesticides in the state to obtain a copy of the buyer’s county-issued permit to confirm legal sale.
Everett credits the Solano County Department of Agriculture for investigating the company and bringing the violations to light.
“The on-the-ground inspections and investigative work of county agricultural commissioners and staff is critical to hold companies in compliance, identify violations early and respond swiftly to keep all Californians safe,” Everett said.
California’s 55 county agricultural commissioners enforce state and federal pesticide laws and regulations, including issuing permits for the use of restricted material pesticides and investigating suspected violations.
“While screening incoming parcel shipments for invasive pests our inspectors identified serious pesticide violations involving restricted use products. Because our staff are cross-trained in pest exclusion and pesticide regulatory programs they were able to quickly intervene and coordinate with DPR to address the violations. Their attention to detail and dedication to their work is critical to making sure our pesticide-use enforcement program works effectively to protect people and manage pests safely,” said Ed King, Solano County Agricultural Commissioner.
The investigation into Keystone began in May 2024 when a Solano County Department of Agriculture biologist encountered four boxes of the weedkiller 2,4-D, addressed to an unpermitted individual, during an inspection at a parcel delivery business. County agricultural commissioner biologists routinely conduct inspections at postal and parcel facilities in search of invasive pests that could harm agriculture.
The product that Keystone shipped to Napa County was involved in a subsequent pesticide drift incident that is the subject of a separate enforcement action by the local county agricultural commissioner. Drift is the movement of a pesticide away from its intended target during or after the time of application.
In June 2024, during a separate parcel facility inspection, a Solano County agricultural biologist encountered a shipment of 2,4-D from Keystone addressed to a person in Benicia who did not have a county permit to use it.
In addition to the licensing action, DPR is proposing $105,000 in monetary penalties.
About the California Department of Pesticide Regulation
The California Department of Pesticide Regulation protects human health and the environment by fostering safer and sustainable pest management practices and operating a robust regulatory system to monitor and manage the sale and use of pesticides across the state. DPR’s work includes registering all pesticides sold or used in California, conducting scientific evaluation of pesticides to assess and mitigate potential harm to human health or the environment, investing in innovative research to encourage the development and adoption of integrated pest management tools and practices, monitoring for pesticides in the air and water, conducting outreach to ensure pesticide workers, farmworkers and local communities have access to safety information, and enforcing pesticide regulations in coordination with 55 County Agricultural Commissioners and their 500 field inspectors.
