OPM is within 3km of the corporation's land - Spring Park in Bromley. Director of open spaces Sue Ireland is also chair of the OPM steering group of the Forestry Commission's regional advisory committee for London and the South East.
The commission linked her and designer Helen Elks-Smith when it decided it could not sponsor the garden that Elks-Smith wanted to create at Chelsea to raise awareness of the problem.
Ireland said: "It's important for us to tackle this issue and for everybody to work together. OPM doesn't travel very far, it's not like Chalara. There's a real opportunity to come in and stamp it out."
The steering group was able to persuade secretary of state for the environment Owen Paterson to find an extra £2m to tackle OPM in London and an extra £1.8m has been committed across the capital by parks bodies. The corporation has spent £4,500 this year.
"The outcome of our work is that we've got half the nests this year than we had last year," said Ireland.
The City of London is responsible for around 4,450ha of open spaces, including Epping Forest and Hampstead Heath, where trees are 50 and 70 per cent oak respectively.