On March 23, as the coronavirus pandemic put grocery workers on the front lines of a public health crisis, Trader Joe’s sent a memo to store managers encouraging them to relay a message to employees: Joining a union might be a bad idea.

“It’s not like buying toothpaste you don’t end up liking,” said the email, which listed a series of anti-union talking points, including a warning about the size of dues. “It’s like buying a house … you’re in for the long term.”

The pandemic has led to a wave of worker activism in recent weeks, as employees at Instacart, Amazon and Whole Foods have gone on strike and demanded increased protections. At Trader Joe’s, a chain known for its outwardly cheerful work force, employees have criticized what they describe as the company’s haphazard response to the crisis, reigniting a debate about union organizing that has simmered for years.

Workers hoping to form a union recently circulated a petition calling for Trader Joe’s to offer “hazard pay,” or an hourly rate of time and a half. And over the last few weeks, the Retail, Wholesale and Department Store Union has held talks with employees.