Weed Potential 
As a weed Willow is invasive in regions with a high water available appearing around streams, lakes and ponds on the coast and inland. There are various species and sub species that are regarded as weeds but generally Willows compete for space, nutrients and water. They reduce light inhibiting the regeneration of local native tree or shrub seedlings. 

They also alter water courses and creek banks by capturing large amounts of sediment with there extensive root systems. They grow in an open sunny position on moist fertile soils. 

Female trees produce seeds between 3 to 8-years and the seeds are dispersed by wind and water. Willows are also dispersed vegetatively as twigs, branches or roots are physically moved by water, machinery or in garden waste taking root when settling in moist soils.  

Control methods include physically digging out seedlings and small plants when the soil is moist ensuring that the roots are removed as the young trunks snap off easily. This material and fruiting branches should be bagged and destroyed. Large pieces of the tree should be removed off site and placed in a very dry open position. 

Young trees can be cut and painted on the stems with the sap wood revealed or larger trees can be drilled at the base and injected with a non-selective herbicide during early autumn. Young plants or seedlings may be sprayed with a non-selective herbicide during spring while the plant is actively growing. 

Follow up applications may be requires as the saplings can re-shoots.

Dead trees along water courses should be cut down and removed before they collapse and block water courses or cause other damage.