Object Disposed exception and multi thread application

I have an application that start System.Threading.Timer, then this timer every 5 seconds read some information from a linked database and update GUI on main form of application;

Since the System.Threading.Timer create another thread for the Tick event, i need to use Object.Invoke for updating User Interface on the main Form of application with code like this :

this.Invoke((MethodInvoker)delegate()
  {
       label1.Text = "Example";
  });

The app work very well, but sometimes when the user close the main form and then close the application, if the second thread on timer_tick event is updating the user interface on main thread the user get an ObjectDisposedException.

How can i do for stop and close the threading timer before closing the main form and avoiding then Object disposed exception ?