Enfield Council says it has carried out extensive works over the years to protect the historic Oak, but even more needed to be done. Councillor Chris Bond, said:
"Our primary objective is to save this fantastic natural monument which predates the Magna Carta. Doing nothing is not an option, because unless we take decisive action, this historic and much loved tree will fall over.
"If that were to happen the it would cause extensive damage to the park and potentially damage nearby homes. "The action we are proposing, while drastic, gives the tree a good chance of recovery and means that future generations can enjoy it for years to come."
Specialist tree surgeons are installing slow release chemicals to encourage the roots to grow. They will also use a crane to remove a number of the heavier limbs to prevent the tree from falling or blowing over.
Enfield Council is trying to save one of London's oldest trees from dying. The 800 year old Minchenden Oak in Southgate dates from the time of the ancient Forest of Middlesex.
The tree has begun to subside and could pose a threat to nearby homes. It has extensive internal decay despite earlier attempts to stop it spreading.