Weed of the Month: Willow

Posted on 1 May, 2025 by Bonnie Humphreys

Willows (Salix species) are a weed of national significance (WONS) and are listed as a ‘restricted’ noxious weed in Victoria under the Catchment and Land Protection Act 1994. Willows were introduced to Australia in the 1860’s by European settlers as ornamental plants and then for erosion control. They occur worldwide but are mostly indigenous to the Northern Hemisphere. In Australia there are around 100 species (including hybrids and cultivars), with around 15 occurring in Victoria, and many are very serious environmental weeds. They grow as trees and shrubs and due to the frequency of hybridization they can be very difficult to tell apart.

Willows grow in moist situations and thrive along streams and wetlands where they are particularly invasive. The CRC for Australian Weed Management believe that they have only invaded about 5% of their potential range within temperate Australia, meaning that without control their reach could be much more extensive. Willows change the function of our stream systems and wetlands in many ways, impacting the ability of our native fauna to use the systems, and reducing the presence of our native vegetation. They can impact native ecosystems by;

The production of dense fibrous roots which slows the flow of water and covers the bed of streams, smothering rocky crevices and feeding grounds for fish and animals instream.
Their deciduous leaves, unlike our local flora, drop at one time of year, smothering and then starving our macroinvertebrates who break down this matter.
Crowding out native flora resulting in reduced resources for fauna.

Willows spread through seed and also stem fragments, which, when disturbed, readily break off and grow.

Finding the right control method for your situation is important to reduce spreading plants further. This may include a combination of methods such as ‘drill and fill’, ‘cut and paint’ or manual removal. As willows are dormant for some of the year (mostly over winter) it is important to only apply herbicide when they are actively growing. If treating with chemicals, it is also important to leave plants in place after treatment to ensure the chemical moves through the plant and completely kills the plant. If using manual removal remove any stem fragments to stop them from taking root and growing in a different place.

For more information head to the Weeds Australia website – click here

To access the Willows Fact Sheet, head to the North Central Catchment Management Authority (NCCMA) website – click here

The Weed of Month article is a segment from Connecting Country’s ‘Partnerships Against Pests’ project funded by Agriculture Victoria in 2024-25. Through this program, Connecting Country is working closely with local community groups, such as Landcare, to raise awareness of local pest plant and animal issues, with the aim to empower community with the skills to address these threats. The project includes seasonal awareness campaigns around key pest issues as well as workshops, and market stalls across the region.

Photo: Connecting Country archives