Growing cereal crops in Scotland has become increasingly "unpredictable and difficult", farming body NFU Scotland (NFUS) has warned.
It said "unusual weather" had resulted in this year's spring barley being ready to harvest earlier than usual - but it had also adversely affected the quality of the grain.
A dry spring affected the germination of barley in some places before later dry weather had a further impact.
NFU Scotland told BBC Scotland: "This year's spring barley harvest is coming in around two weeks earlier than usual – something we've not seen before."
Barley sown in spring is often sold for making whisky, while winter-sown barley is traditionally used for animal feed and sometimes brewing beer.
An NFUS spokesperson said: "The unusual weather we've had this year has not only caused the early harvest, it has also affected the quality of the grain, particularly in malting barley – a major Scottish crop.
"If the grain doesn't meet maltsters' specifications it could be rejected, causing a serious loss of income for some businesses."