Weeks of drought have turned much of Ontario’s prime agricultural land into a dust bowl. And it is corn farmers, especially in the southwest and eastern parts of the province, who have been the hardest hit.

“It is a bad year in eastern Canada and it is getting worse,” said Evan Fraser, a geography professor who studies global food security at the University of Guelph, west of Toronto. The far southwest part of Ontario is “looking grim,” Dr. Fraser said, and in other parts of the province “it’s a bit of a wait-and-see game.”

Although many parts of Western Canada have experienced an excellent growing year, the east is parched. In Quebec, fruit is wilting on trees and Atlantic Canadian farmers are seeing their crops bake in the heat.

In Ontario, some parts have received less than half of the normal precipitation for this time of year. The weather over the next week or so will dictate how much of the Ontario corn crop survives and it will take several days of sustained rain to make a difference.

“We’re at the mercy of Mother Nature right now,” Dr. Fraser said. He points out that there should still be a lot of corn available because so much was planted in the United States.

Ron Miller of Miller’s Farm and Market near Manotick, south of Ottawa, said he estimates his corn harvest will be about 60 per cent of the normal yield. “It’s been mediocre,” he said. “Some of the land is better than others.”

A downpour blew through his region on Monday and Mr. Miller said he is waiting to see whether it helped. But he said he cannot remember a drought of this magnitude since 1965.

The federal New Democrats are calling on Agriculture Minister Gerry Ritz to say he is willing to leap to the rescue of farmers.

Malcolm Allen, the agriculture critic for the NDP, told a news conference on Tuesday that it is too late for many Ontario grain growers to salvage anything from this growing season.

“The crops are literally burned off the land,” Mr. Allen said. “This is a huge issue for eastern Canada and we need the minister to be on the ground and talking to farmers now about the risk they are facing with this drought.”

Mr. Ritz said his officials are monitoring the situation and working with farmers to support them during this difficult period.

But, since neither the farmers nor the Ontario government are asking for help, it is unclear what other assistance Ottawa could provide at this juncture.

Barry Senft, the CEO of the Grain Farmers of Ontario, said 80 per cent of Ontario farmers are protected with crop insurance, which will lessen the financial impact of the dry conditions. Claims for losses will not be coming in until later in the year when the extent of the damage can be fully assessed.

The Ontario government says a call now for federal assistance would be premature.

“At this point we are not asking them [the federal government] for anything specific,” said Mark Cripps, a spokesman for Ontario Agriculture Minister Ted McMeekin. “We won’t know what yield losses are until harvest time so it’s pretty hard to ask for disaster relief.”

And Ontario has an effective suite of risk-management programs to protect farmers that will cover most losses and help producers who need interim financing, Mr. Cripps said.

Ben Bradshaw, another University of Guelph professor who studies agriculture management, said research shows that one-off bailouts in extreme circumstances like droughts are not as effective at ensuring the sustainability of farms as convincing farmers to manage their own risks with crop insurance and by producing crops that are more resilient.

“Bailouts make sense in terms of popular opinion,” Dr. Bradshaw said, “but it’s no basis upon which to run agriculture policy.”