Twelve haystack fires in little more than three months have put firefighters on heightened alert in the Wimmera.
CFA crews are grappling with a spike in calls across Western Victoria this summer, with another 38 haystacks going up in smoke across an area spanning Mildura to Kyneton.
Fires in the Wimmera have included 1000 bales that erupted in flame in Arapiles, west of Natimuk, the same day a total fire ban was declared.
Firefighters in Horsham say part of the of the problem is the number of bales not made to industry standards.
"[They] were stored away with too much moisture," CFA district 17 commander Lindsay Barry said.
"Green or damp hay is susceptible to overheating, so those two in combination will make a fire."
A wet summer had intensified the risk of water getting into bales.
"The hay has been pressed for so long, and because of the summer we've had, the majority of fires are where hay has been stored outside and exposed to the elements," Mr Barry said.
He urged farmers to be vigilant and make sure they were regularly checking bale temperatures.
"If they are warm, put measures in place to break down and separate the stacks and use machinery to put in strategic breaks if you can."