Tree Weeds

Over the last 150 years or so many exotic trees have been imported into Australia only to discover many have weed type characteristics spreading out of there original placement out into the landscape by fruit and seeds eaten by birds, foxes, also spread by wind and water. Examples are hawthorn, wild cherry, willow species, box elder, desert ash, cape wattle, pine and tree tobacco. Problems occurring:`

• They take up lots of physical space
• They can create impregnable barriers of thickets
• They have a large area of soil occupied by roots
• They sometimes send up suckers a long way from the parent plant even have the original tree has been removed. A good example here would be Elm trees
• They alter the microclimate
• They may alter the soil chemistry
• Willows clog up waterways

Weedy trees favour the growth of other weeds beneath their canopies. They provide additional perching and roosting places for birds from which weed seeds are deposited in droppings. ‘Bird poo haloes’ containing numerous bird dispersed weeds such as boxthorn, bridal creeper sweet pittosporum and blackberry.
Weed trees can be removed by cutting down as close to the base as possible and pasting glysophate herbicide on the cut stump surface. This must be done with 10 to 30 seconds of the cut being made otherwise the stump will seal it self and chemical will not penetrate. The tree should not be under stress; normally spring to early summer gives best results.