Getting stuck behind tractors during the summer is a recipe for road rage, warns a farming union, which is urging drivers to pull over.
A driver's worse nightmare - being stuck behind a queue of tractors
The Farmers' Union of Wales is calling on drivers of all slow-moving vehicles to defuse road rage by moving over and allowing faster traffic to pass.
The union admits that being held up by a tractors is a frustrating experience.
The RAC welcomed the move but urged tractor drivers to ensure it was safe to pull over.
Farming leaders add that although tractors are often blamed for hold-ups, slow-moving lorries and cars towing caravans are also at fault.
"Getting stuck behind a slow moving vehicle on a twisting country lane with no opportunity to overtake is a very frustrating experience," said Nick Somerfield, chairman of the FUW's land use committee.
"It is especially annoying on hot summer days for local people who are anxious to keep appointments and for tourists whose enjoyment of their holidays can be spoiled.
"The thoughtlessness of some drivers who forget to pull over when they are being followed by a long line of traffic is a recipe for road rage.
Farming leaders are also urging cars towing caravans to pull over
"It can often lead to drivers taking unnecessary risks and overtaking at the most inopportune times, creating a danger to themselves and to other road users."
Mr Somerfield, from Bethlehem, in Carmarthenshire, added: "The Highway Code states that anyone causing traffic to back up as a result of their slow speed must pull over at the earliest and safest opportunity to allow faster vehicles to pass.
"The FUW is reminding all drivers of slow moving vehicles to think of other road users and to follow the Highway Code."
The RAC welcomed the advice, provided it was safe for tractor and caravan drivers.
"It's not always the case that it's safe to pull over so we would urge drivers of slow-moving traffic to make sure it's safe to pull over before doing so," said a spokeswoman.
"If it is safe then I think drivers of faster vehicles will welcome it."
Montgomeryshire AM and mid Wales farmer, Mick Bates, said: "I always pull to the side when I'm towing a big trailer and there's no excuse not to do it nowadays as tractors have large mirrors.
"It's not like the old days when you had to keep turning round to look at the traffic. However, it's also important for car drivers to realise that farmers have a job to do and sometimes they are going to be held up.
"Sometimes it's difficult for farmers to pull over safely."