Thieves are stealing satellite steering equipment from tractors parked in fields and farmyards.
A spate of thefts has seen specialist satellite receivers and display screens stolen from tractors in Norfolk and south Lincolnshire.
Some 17 farms are believed to have been targeted during the past three weeks. John Deere Greenstar satellite systems are among the systems being stolen.
Carl Pitelan, FarmSight consultant with Norfolk John Deere dealer Ben Burgess, said all types were being targeted – from the oldest to the newest.
“Lock them up and keep them safe,” he wrote on Twitter.
The latest incident was reported in the Swineshead area on Friday (24 May). A similar theft occurred at a farm at Moulton Seas End overnight between 19-20 May. A further theft occurred on the night of 16-17 May.
Earlier, a satellite steering device was stolen while a vehicle parked up secure at a yard in the Spalding area on the night of 13-14 May.
Police are urging farmers to ensure vehicles are left secured and that anything with a high value is taken out of the vehicles when leaving them unattended.
Community policing inspector Jim Tyner said: “The fact is that if tractor users don’t remove these items, there is a chance that a thief will.”
Farmers are being asked to remain vigilant and call 101 if they see anyone acting suspiciously in or around farm machinery.