Ontario corn farmers are taking stock of their parched crops after scattered rainfall over the last 36 hours, but many say they'll need a lot more rain to avoid failed crops.

Stittsville farmer Don Kenny said he was in a good mood after a rainsquall this week left his corn damp, the first time the crop got any significant rain since June 10.

"This is a critical point for the corn, because it's tasseling and then pollinating the cobs down below," said Kenny. "Timing-wise, the half-inch of rain that we got today was very fortunate. It'll help this corn go ahead and pollinate the cobs."

Weeks of drought has come at a bad time for Ontario's corn farmers. (CBC)

Kenny's field is one of the few in eastern Ontario where every cornstalk has a healthy tassel on top. He has another field where the corn is four feet high and has no tassels, meaning cobs with no corn.

And even for his good corn, the impact of the rain won't last for long.

"This time of year, corn needs about two inches a week," he said.

Driest season in 40 years

Cumberland farmer Francis Proulx said it's the driest season he's seen in at least 40 years.

"It's so dry it's not pulling any moisture from the ground. You can see the leaves are all yellowing at the bottom," said Proulx, who has been able to irrigate some of his 25 acres at great expense.

"Right now it's very, very serious. If it doesn't rain in the next week a lot of farmers will lose their crops," he said.

Some farmers in the region have already called crop insurance and are declaring the year a write-off.

Futures contracts on corn and soybeans are heading toward record high prices. Drought has also hit the real heartland of corn in the US Midwest.

"There's going to be a food shortage for sure. The drought is too widespread," said Proulx.