Boxthorn

Physical control

Physical control should be carried out when there is no or minimal seed on the plant.  Boxthorn is deep rooted so considerable effort is required to physically remove boxthorn.  For large plants winching and pulling of boxthorns offer least disturbance of the mechanical methods, however chemical control is necessary to treat regrowth from strong root systems.

Large plants

• Winching: using rigging at the base of plant connected to a consistent force e.g. vehicle to pull plant out and as much of the root system as possible.
• Pulling: using a front-end loader, articulated loader or excavator to pull out entire plant and as much of root system as possible using hydraulic arms attached to the front of machinery. A hydraulically operated puller has been commercially developed specifically for the removal of African boxthorn.
• Bulldozing, stick raking and blade ploughing should be used in more disturbed areas where the surrounding environment is less sensitive. This is a rapid control method and is suitable for moderate to heavy infestations.

Small plants

• Seedlings can be hand pulled in soft soil to ensure complete root system is removed.

Chemical controls

Foliar sprays to be applied in active plant growth in spring or post rain, monitoring and follow ups are essential for effective control and suppression of boxthorn, this is best done in autumn. Boxthorn sheds its leaves when stressed so foliar spray is not the most reliable control method. All foliage must be covered during application.

Foliar spray in 100L of water -  1L Glyphosate (450g/L) + 10g metsulfuron-methyl (600g/kg).

Basal bark: around the base of stems when the plant is a maximum of approx. 50mm in diameter and a height of 30-40cm above ground level. Treat with a mix of triclopyr (600g/L) at a rate of 2L/60L of biodiesel (Department of Environment and Water, 2024).

• Triclopyr, along with triclopyr–picloram-based herbicides (mixed with diesel)

Cut and swab: cut each stem at ground level (no more than 15cm above ground) and apply herbicide to the cut stem immediately (can be sprayed or painted). Apply a 3-5mm thick layer of gel to freshly cut stump. Noble et al (2021) lists the following herbicides and mixes and states that this method is best for when faced with poor vehicle access areas, and allows dead boxthorn debris to be removed which reduces invasive fauna habitat and protects native fauna, humans and vehicles (ridding thorns).

• Triclopyr–picloram mix (in diesel),
• Triclopyr (mixed with diesel),
• and picloram are suitable for this technique.
• Glyphosate (mixed 1:1 with water) has been used successfully with the cut stump technique over many years by Friends of Bass Strait Islands (Ziegler and Hopkins 2011).

Root application: when the soil is wet or rain is expected (Land Protection 2006), apply a residual herbicide to the soil between the base of the plant and the drip line. Do not use this technique in environmentally sensitive areas. Only suitable in highly disturbed areas, where native bushland is not present.

• Tebuthiuron is applied to the soil near the drip line of the target plant
• Picloram-based herbicides can be used for stem-injection application, while glyphosate-based herbicides can be used for frilling or stem-scrape techniques (Noble and Rose 2013). 

Biological control

Puccinia rapipes (boxthorn rust fungus) is a biological control agent for boxthorn.  As of 2026 it's in the early stage of release trials.  For more information see CSIRO Boxthorn rust fungus.