MINNEAPOLIS — The first of tens of thousands of U.S. lawsuits will go to trial on Monday against Swiss agribusiness giant Syngenta over its decision to introduce a genetically engineered corn seed variety to the U.S. market before China approved it for imports.

The lawsuits allege Syngenta’s move wrecked an increasingly important export market for U.S. corn and resulted in price drops that hurt all producers. Court filings show Syngenta aggressively marketed the seeds even when it knew Chinese approval was going to be a problem.

Plaintiffs’ experts estimate the economic damage at about $5 billion, though Syngenta denies its actions caused any losses for farmers.

Monday’s trial in state court in Minneapolis will mark the first test case. The second goes to trial in federal court in Kansas City, Kansas, on June 5. The two cases are meant to provide guidance for how the complex web of litigation in state and federal courts could be resolved.