FRESNO, Calif. (AP) — Authorities who spent the past decade targeting marijuana growers in the Sierra Nevada wilderness have turned their attention toward California’s agricultural heartland — the nation’s richest farmland — which they say is the new hot spot for illicit growers, their guns and toxic pesticides thanks to medical marijuana laws.

At a news conference Wednesday, authorities announced results of a summer-long enforcement effort in the state’s agricultural heartland: 175 local and federal arrests, along with 100 guns, $4,869 in cash and 400,000 plants seized across hundreds of thousands of acres.