VIEUX MANOIR, France — The wheat harvest is winding down here in northern Normandy, the last region in France to bring in its crops. Farmers here say this promises to be a bumper year, but that doesn’t mean they are happy.

Over the past month, farmers across France have taken to the roads to protest their anger at a drop in meat and milk prices, sporadically throwing up barricades of tractors and burning tires on main highways and near popular tourist sites. Here in the Seine-Maritime region, more than 500 farmers blocked bridges across the Seine in late July.

“Livestock farmers are having a very difficult time,” said Sébastien Windsor, president of the local Chamber of Agriculture. “This has led to discouragement and yes, anger.”

Mr. Windsor, who grows grain and raises pigs on a 500-acre farm, points to falling prices that are unsustainable for farmers. In a region known for its dairy cows, milk prices have dropped 25 percent since 2014 to 300 euros per 1,000 liters — roughly $330 per 265 gallons — about €40 less than production costs. Meat prices have fallen about 20 percent since 2013, partly because of Russia’s embargo imposed last year in response to European Union sanctions against Moscow’s aggression in Ukraine.