Keep a pen or pencil and paper handy to record license numbers of vehicles or other information connected to suspicious activity. Remember that many cell phones can be used to take photographs.

“Your employees are your eyes and ears, and it’s OK to question somebody,” said Ryan Jacobsen, executive director of the Fresno County Farm Bureau. He and others said heightened awareness of any suspicious activity is vital.

Take note of people taking photographs, videotaping, using binoculars or doing sketches. “We’re not talking about people taking pictures of blossoms,” said Fresno County Sheriff Margaret Mims. Instead, she said, taking pictures of storage areas, for example, could arouse suspicion.

Harden known likely targets of theft or terrorism. Identify vulnerable assets and take steps such as marking equipment with an identification number and controlling access points for delivery vehicles.

Crime stopper lines can be used to great effect, and it is often the criminals who report each other. “There is no honor among thieves,” Jacobsen said.

Mims advises: “See if people are doing surveillance or asking probing questions about security. Trust your gut.”

Be aware of quarantined areas, said Carol Hafner, Fresno County agricultural commissioner and don’t “pack a pest.” Report pests promptly she said: “Call us, we’re the bug cops.” Take pictures with the pest beside a dime, she said, and collect a specimen. If plant material figures into an issue, put it in a sealed plastic bag.

Let authorities know of the death of a large number of livestock or significant crop losses that are not weather-related, said Tom Knowles, a retired FBI agent and authority on terrorism.

Report the theft of chemical sprayers.