New York: A jury in California has awarded $US289 million ($395 million) to a former gardener who said he got terminal cancer from Roundup, a widely used weed killer made by US agro-chemical giant Monsanto.

The jury awarded $US250 million in punitive damages and more than $US39 million in compensatory damages to DeWayne Johnson who was diagnosed with lymphatic cancer at age 42 in 2014.

He is one of hundreds of cancer patients suing Monsanto, with Friday's development potentially setting a precedent for other cases against the company.

Johnson's case had been moved up to be heard ahead of others because he is dying.