Waging war on coffee bush

Coffee bush (Leucaena leucocephala), a highly invasive woody weed, is one of the more abundant weed species found in Minyirr Park. Its presence in the park is a threat to the only patches of culturally and ecologically significant Monsoon Vine Thickets on Yawuru Country. Also known as ‘sneaky bush’, it can grow almost unseen in sheltered and shaded areas of dense vegetation.

The Yawuru Country Managers and the Department of Biodiversity, Conservation and Attractions (DBCA) have been working to control weeds in Minyirr Park and protect the endangered Monsoon Vine Thickets, yet the continued presence of weeds is one of the biggest threats to the health of the park.

Volunteers Kirrily Preist and Courtney Brown using the cut and paint method with Vigilant II Gel Herbicide. Photo: Hamsini Bijlani

In order to help make management easier and more effective, Environs Kimberley staff and volunteers conducted a yearlong trial to understand what chemical methods are best for controlling coffee bush in Minyirr Park. We found that different treatments worked best on different sizes, or life-stages, of coffee bush:

• The best way to treat small seedlings is to hand-pull them during the wet season when the soil is soft.
• The most effective way for treating larger seedlings and saplings with a diameter smaller than 2cm is to cut them down at the base using loppers or secateurs, and paint the cut surface with Vigilant II Gel Herbicide.
• Basal-barking with a mixture of Access Herbicide and diesel (in the ratio 1:60) was found to be the most effective way to treat big coffee-bush trees, with a 70% success rate. It has a 53% success rate on seedlings and saplings. Basalbarking entails saturating the entire circumference of the plant with the mixture, from the ground up to a minimum height of 30cm. This is a great option if you do not have access to chemical herbicides but still want to get rid of coffee bush.

This trial was part of a larger Monsoon Vine Thicket project conducted in partnership with the Yawuru Country Managers, Bardi Jawi Rangers, Nyul Nyul Rangers and the Department of Biodiversity, Conservation and Attractions, and funded by the Western Australian Government’s State Natural Resource Management Program.

Written by Hansini Bijlani