German pharmaceutical giant Bayer has said it is now targetted in some 18,400 US legal cases over glyphosate, a key herbicide ingredient that plaintiffs say caused grave illnesses such as cancer.

"As of July 11, 2019, lawsuits from approximately 18,400 plaintiffs had been served in the United States in connection with the crop protection product glyphosate," Bayer said in a statement.

In April, the number of cases stood at 13,400.

The wave of lawsuits has crashed onto Bayer since its takeover of US seeds and pesticides maker Monsanto last year for $63 billion, one of the largest foreign mergers ever by a German company.

In the first few cases to be heard, juries in lower courts have found in favour of plaintiffs, agreeing that blood cancer non-Hodgkins lymphoma had been caused by glyphosate-containing products, including Monsanto's flagship Roundup weedkiller.

In post-trial revisions of the verdicts, judges have stopped short of overturning jury decisions while reducing damages awards.

Last week, a spectacular two-billion-dollar payout was slashed to $87 million in the case of California couple Alva and Alberta Pilliod.

Bosses say they are confident that the weight of scientific evidence is on their side and that they can prevail before American appeals courts, which do not have juries.

Bayer "continues to believe that it has meritorious defences and intends to defend itself vigorously" it said.

In the group's second-quarter earnings, also released today, Bayer reported net profits fell 49.1% year-on-year to €404m.

Operating, or underlying profits before special items, grew 4.5% to €1.8bn, while revenues rose 21.1% to reach €11.5bn.

Among its three major divisions, the agrichemical unit was hit hard by flooding in the US, drought in Europe and Canada, and global trade conflicts.

Meanwhile, the pharmaceutical division reported sales growth based on blockbuster drugs like eye medicine Eylea and anticoagulant Xarelto.

The over-the-counter medicines unit also increased sales as both demand and prices for household-name products like Aspirin grew.

Looking ahead to the full year, Bayer stuck to its forecast of revenues of €46bn, up around 4% on 2018, with operating profit before special items of around €12.2bn.

"However, this outlook is becoming increasingly ambitious in view of the challenging environment" for its agrichemical business, the group said.