Two trucks barrelling into eachother has caused grapes to spill onto State Highway One in Riverlands - leaving drivers seeing red

Police say the crash between the harvesting trucks happened at around 3.40 this afternoon, just south of Blenheim.

The road is under stop-go traffic management and motorists are advised to avoid travel - or face significant delays.

Waka Kotahi says a 30-kilometre per hour speed limit is in place.

No injuries have been reported.