Bayer shares fell on Thursday, with traders citing a report by German weekly WirtschaftsWoche saying farmers in Arkansas and South Dakota had filed new class action lawsuits against Monsanto and against BASF with a St. Louis court.

The cases, which were directed at number of other companies, "have been known about for quite some time, and media from the United States and Germany have already reported on this matter", Bayer said.

Reuters previously reported that farmers were already suing dicamba manufacturers, claiming crops were damaged by neighbours' use of dicamba-based weedkillers.

Older versions of dicamba are known to easily evaporate and travel to off-target plants but makers of next-generation dicamba, also including DowDuPont, say the new products address the issue - provided farmers adhere to label instructions.

(Reporting by Ludwig Burger)