76-year-old Pamela Greenslade was driving the telehandler to transport silage bales from her farmyard to a shed to feed her cattle at Fernicaps Farm in Wiveliscombe, Taunton.
Taunton Magistrates' Court heard Ms Greenslade had not been trained to use the telehandler. The man who normally operated it was trained but was unavailable that day.
The Health and Safety Executive (HSE), prosecuting, told the court that on 31 December 2009, Ms Greenslade had asked a neighbour, John Morrish, 49, to remove plastic wrapping from the last bale when she had brought it to the shed.
As Mr Morrish was cutting the wrapping off the bale, which was still being held by the grab of the telehandler, Ms Greenslade moved the machine, trapping him between the machine and the feed barrier in the shed, breaking his ribs and puncturing a lung.
After the hearing HSE inspector Tony Makin, said: "Telehandlers are very useful machines for farm work, but all too often they cause incidents when people use them without formal training. Because they can be so dangerous, it's a legal requirement that anyone using these machines is properly trained to do so."
Ms Greenslade pleaded guilty to breaching Section 3(2) of the Health and Safety at Work etc Act 1974 and was fined £6,000.