FRANKFURT, Germany (AP) — Bayer AG board chairman Werner Wenning is stepping down from his post at the drug and chemical company, which is facing a major legal battle over its Roundup weed killer.

Wenning, who is 73, said he had planned to leave last year but was asked to stay due to “the company's situation at the time.” His current contract runs through 2022.

He will be succeeded at the company's April 28 board meeting by board member Norbert Winkeljohann, 62, the company said in a news release Wednesday.

Wenning has served as board chair since 2012. He joined the company in 1966 and rose to become CEO before moving to the board. He was board chair during the company's 2018 acquisition of U.S. seed and farm chemical company Monsanto. The acquisition turned into a problem for the company after it inherited exposure to legal troubles involving Roundup. Thousands of lawsuits filed in U.S. states and federal courts say Roundup has caused cancer in users. Monsanto's owner, Bayer, denies such allegations and says the product is safe.

Groundskeeper DeWayne Johnson was awarded $289 million by a California jury in the first Roundup case to go to trial. The award was later reduced to $78.5 million and is currently being appealed.

Shareholders have criticized Bayer management for underestimating the risks when it took over Monsanto.