The incident happened in Beddingham Road, Tarring Neville at around 10.45pm.
A spokesman for East Sussex Fire and Rescue Service (ESFRS) said: “Four appliances from Newhaven, Seaford, Lewes and Roedean initially attended.
“Sussex Police closed the A26 due to smoke causing visibility issues.
“There were no injuries to humans or livestock.
“We have now left the scene and the incident has been handed over to the landowner.
“A controlled burn is now taking place and we will be sending an appliance over to ensure that this is happening safely.
“A fire investigation will take place once the controlled burn has been completed.”