Ageratina adenophora

Mexican devil

Family: Asteraceae

Origin: South America

Close up of Mexican Devil seed pod.
Grows in any location and produces many seed that can be spread by wind. Often found in disturbed areas like roadsides and plantations.
Photo credit: Forest and Kim Starr

Regional Pest Management Plan (RPMP) status

  • Whole region — Sustained control
  • Hauraki Gulf Controlled Area Notice pest

View more about the RPMP statuses

General description

Herb to sub-shrub. Stems are woody at the base, mostly erect, and can form adventitious roots. Leaves are < 8 x 7 cm and diamond-shaped. Flowers are white, < 7 mm in diameter and borne in dense clusters in August – March. Seeds are black and ripen in late summer-autumn.

What you need to know

To help protect our environment, from 1 September 2021, you:

  • will not be allowed to breed, distribute, release or sell Mexican devil within the Auckland region.
  • will not be allowed to plant Mexican devil within the Auckland region, unless you are transferring an existing plant on your land to another location within the boundaries of the same property.
  • must destroy any Mexican devil on land that you occupy if it has been planted in breach of the above rules and you are directed to do so by an authorised person.

Habitats

Open and lightly shaded habitats, wetlands, gumlands, shrublands, forest and riparian margins, coastal forest, estuaries, roadsides, disturbed sites, plantations.

Dispersal

Seeds dispersed by wind and water. Vegetative spread from stem layering.

Impact on environment

Competes with and displaces native plants in wetland and riparian habitats. Allelopathic and may alter soil microbial activity. Poisonous and potentially fatal to horses.

Control

Site Management

Easiest to control at onset of flowering from August to January. Follow up treated areas 3 times per year. Encourage natural regeneration of native plants or replant treated areas where possible after 2-3 treatments to establish dense ground cover and minimise reinvasion.

Recommended approaches

Physical control

Method: Dig out.

Plant parts requiring disposal: All parts.

Disposal options: Remove to greenwaste or landfill.

Biocontrol

Biocontrol is currently not available for this species.

Community agrichemical control recommendations

Basic Growsafe certified: Foliar spray with 200ml glyphosate green per 10L of water.

Certified Handler/Experienced agrichemical user: Foliar spray with 200ml glyphosate green per 10L of water and 20ml penetrant.

Caution: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.

Small Mexican Devil plants.
A herb that can get woody stems as they mature. Large diamond-shaped leaves with white flowers.
Photo credit: Jonathan Boow