Farmers in Scotland are 'overly-reliant' on subsidy support and are not prepared for post-Brexit competition that will arise.
Agriculture and Horticulture Development Board (AHDB) chief strategy officer Tom Hind said Scottish farming will have to become less dependent on UK support after Brexit and many are not prepared.
Mr Hind was speaking at the annual conference of farm co-op support organisation SAOS in Dunblane.
"I don't think we are doing enough to start laying the ground for the changes we might see and I think we need to start doing that now," he said.
"The World Trade Organisation places some limits on what the UK can do. We cannot, for example, put in place some massive protectionist policies."
Mr Hind said losing free trade access with the European Union would mean paying tariffs.
"For agricultural goods they are particularly high. In the region of between 15% for cropping sectors right through to 50-60% for livestock products, particularly meat products."
'Marked differences'
NFU Scotland President Allan Bowie had a meeting with government ministers in London in December and said Scottish Brexit could differ with the rest of the UK with regards to farmers.
"There is strong recognition that Scottish agriculture’s needs from Brexit negotiations will differ from the rest of the UK and that this must be a factor under any future arrangements.
"There are already marked differences between different parts of the UK.
"In Scotland, for example, we have opted to use part of our existing support package to target key sectors like beef and hill sheep and the ability of Scotland to make such decisions will clearly need to be maintained."
Mr Bowie added: "That requires a future UK agricultural policy that is truly representative of all parts of the UK and recognises the differences and the drivers of the industry in Scotland.
"We must make the most of the opportunities for our farming, food and drink sectors that Brexit presents. We can support jobs and grow income but only if we prioritise the needs of farming."
