binded treeview in wpf disable nodes

I have a treeview that is bound to a class:

The problem is that I want to add a property that the treeviewitem have, to activate or deactivate parts of the tree, but when I bind an own class, I don't know how to add that property.

Try:

• derive my class from treeviewitem (the bind didn't work for me, maybe I did that wrong)
• add an enable property (it works, but I don't know what to do with that property).
• transform the items of the tree to treeviewitem (it did not work, they are not of that type).

So how do I tell the tree that certain items are disabled (graying them, underlining them, it doesn't matter how, but how so that the user can't click on them).

Tree definition (xalm)

<TreeView x:Name="treeView2" >
    <TreeView.DataContext>
        <Controles:ListaArbol/>
    </TreeView.DataContext>
    <TreeView.Resources>
        <HierarchicalDataTemplate ItemsSource="{Binding Children}" DataType="{x:Type Controles:ListaArbol}" >
            <StackPanel Orientation="Horizontal">
                 <Image Source="{Binding Imagen}"  Stretch="Fill" Width="30" Height="30" HorizontalAlignment="Center" VerticalAlignment="Center" />
                 <TextBlock Text="{Binding texto}"  />
            </StackPanel>
        </HierarchicalDataTemplate>
    </TreeView.Resources>
</TreeView> 

Class that is bound:

public class ListaArbol: TreeViewItemBase
{
    public ListaArbol()
    {
        this.Children = new ObservableCollection<ListaArbol>();
    }

    public string texto { get; set; }

    public string Imagen { get; set; }

    public string Control { get; set; }

    public ObservableCollection<ListaArbol> Children { get; set; }
}

The above class derives from:

public class TreeViewItemBase : INotifyPropertyChanged
{
.....
}

and to load the tree I do something like this:

List<ListaArbol> items = new List<ListaArbol>();
ListaArbol i1 = new ListaArbol { texto = "Archivos", Imagen = "Imagenes/blue-folder-vector.png", Control="ControlArchivos" };
ListaArbol i2 = new ListaArbol { texto = "Consultas", Imagen = "Imagenes/consultas.jpg", Control= "ControlConsultas" };

items.Add(i1);
items.Add(i2);
treeView2.ItemsSource = items;