19 January 2025
The City of Cape Town’s Invasive Species Unit has confirmed Polyphagous Shot Hole Borer (PSHB) beetle infestation of two trees in Pinelands in January 2025. Both trees, a plane and an oak, are in the vicinity of Stellenberg. The Invasive Species Unit will be conducting further surveys in the area and updates will be shared with the community.
NB: Please report suspected infestations outside of the above location to the City of Cape Town’s Invasive Species Unit www.capetowninvasives.org.za.
The PSHB beetle is an invasive tree killing ambrosia beetle that threatens trees within Cape Town’s urban forest.
Trees at risk
Many common landscape trees like plane, oak, willow, coral and especially Box Elder appear to be especially susceptible. Avocado and fig are also susceptible, similar signs and symptoms on other backyard fruit trees are probably due to other pests and diseases.
See https://www.fabinet.up.ac.za/images/PSHB/8-PSHB_host_list_2022-11-14.pdf for a list of susceptible trees.
The impact
In severely infested trees, the PSHB beetle and its symbiotic fungal disease can cause tree decline, branch dieback and tree death. Trees with heavily infested branches can be especially hazardous, as the PSHB beetle’s tunnelling weakens the wood, causing limbs to break and fall.
What to look for
1. Entry holes to the PSHB beetle’s tunnels, perfectly round and less than 1mm wide (about the size of the tip of a medium ball-point pen).
2. Tree symptoms and signs of entry holes. Dark wet staining, thick gumming, sugar like build up. See more photos and descriptions of the PSHB beetle’s attack at https://www.fabinet.up.ac.za/…/3-PSHB…
3.Dieback. Dead branches with wilting leaves may be a sign of severe infection by Fusarium dieback disease.
4. Report any of the above symptoms to the City of Cape Town’s Invasive Species Unit www.capetowninvasives.org.za
What You Can Do
1. Keep your trees healthy. Proper irrigation and maintenance will keep trees strong and help protect them from the PSHB beetle.
2. Check your trees. Look for the common signs and symptoms listed previously. Regular monitoring ensures that infestations are managed early, before they cause dieback and death.
3. Review your management options. When possible, pruning infested branches is recommended. Pruning equipment should be cleaned with 70% ethanol between working on other trees. There in still no legal, safe or effective treatment for the PSHB beetle. Severely infested trees may require removal since they are unlikely to recover and are a constant source of the PSHB beetle that can spread and infest neighbouring trees.
NB: Pruning or felling of infested verge trees is the responsibility of the City of Cape Town. Infested trees within your property boundary, is the resident’s responsibility.
4. Call in a professional. A reputable arborist would be able to provide recommendations based on the condition of your tree within your property boundary.
5. Take care of green waste. The PSHB beetle can survive in cut wood for weeks or even months. Proper disposal of green waste includes chipping of infested wood, followed by composting the chip or solarising it under thick 130 micron plastic for 6 weeks from December to February or 6 months from March to November. If one does have to move green waste, ensure to cover loads in transport to the nearest designated drop off facility.
6. Don’t move firewood. The PSHB beetle and other tree killing insects often reach new locations by hitchhiking in firewood. Please use responsibly sourced firewood to help slow the spread of the PSHB beetle. Purchase firewood locally. Only purchase the amount of firewood you need.
The below informative video is helpful in comprehending the threat of PSHB beetle. https://youtu.be/MLyYUGR-H2c
Material adapted from ishb.org
To report PSHB, Invasive Wasps and EDRR Species please contact City of Cape Town’s Invasive Species Unit on 021 444 2357 or email invasive. species@capetown.gov.za, Alternatively log a C3 notification.