What does it look like?
Mexican devil has lots of stems that grow from the base, and these often die back over winter. The stems are usually purple, feel sticky to the touch, and become woody as the plant gets older. You’ll often see small lumps (called galls) on the stems, caused by a tiny parasitic fly.
The leaves grow in pairs along the stems and are diamond shaped with rounded, toothed edges. From August to December, the plant produces clusters of small white flowers. These are followed by distinctive black seeds that help the plant spread easily.
Why is it a problem?
This is a long-lived species that’s quick to mature and produces many highly viable, well dispersed seed. Drooping stems can take root where they touch the ground. Dense-growing, this species overtops groundcovers and smaller native species. It can also block waterways or at least impede waterflow. Tolerant of moderate shade, damage, grazing, salt, most soils, drought and damp. This species will easily invade a variety of environments, including rough pastureland, strips of land along waterways, wetlands and roadsides.
Control methods
Physical control
Dig or pull out small infestations. Expose roots to dry thoroughly and leave to rot or burn.
Herbicide control
Weed wipe (all year round) using 333ml glyphosate (360g/l) per 1L water, or 2g metsulfuron-methyl (600g/kg) per 1L water. Or,
Spray with 20ml glyphosate (360g/l) + penetrant per 1L water. Or,
Spray with 5g metsulfuron-methyl (600g/kg) per 10L water or 20g metsulfuron-methyl (600g/kg) per 100L water. Add penetrant in winter. Spray lightly, not to run off.
CAUTION: When using any herbicide or pesticide, PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.
More information
Can be distinguished from mist flower (Ageratina riparia) by the broader leaf shape and stalked glandular hairs without stripes.
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