GIRESUN, Turkey—The farmers who produce most of the world’s hazelnuts are reeling from a currency crisis that has shaken a supply chain that stretches from this town’s jagged hillsides overlooking the Black Sea to Nutella jars on supermarket shelves.
The Turkish hazelnut industry—which employs some four million people who produce 70% of the world’s hazelnuts—is a stark example of the potential global implications of an economic gamble set in motion by President Recep Tayyip Erdogan, who says he wants a weaker Turkish lira to encourage exports and expand productive industry. The lira has lost half of its value this year.