The Polyphagous Shot Hole Borer (PSHB) is threatening South African Trees

The polyphagous Shot Hole Borer (PSHB), also known as Euwallacea Fornicatus are able to cause a great deal of damage to our environment, and it has recently been discovered in South Africa.

These beetles are approximately 2mm long and is native to South East Asia, which means that the beetle has no natural predator in South Africa and can spread like wildfire.

To make matters worse, this beetle has a symbiotic relationship with certain types of fungi, like Fusarium Euwallacea. The fungus is the beetles’ main source of food in addition to it being the main cause associated with the wilting of trees. The beetle is believed to use the other types of fungi to help with colonisation of infected trees.

This beetle along with the associated fungi, has caused tremendous damage to trees across the US (specifically California) and regions of the Middle East. Considering the devastation caused by this beetle in Sandton and in Knysna (currently infesting over 200 indigenous tree species from 28 different plant families) this beetle could cause one of South Africa’s largest ecological tragedies.

 

How does the beetle infest the tree?

The beetle itself, does not kill the tree, but the fungus accompanying the beetle does. The fungus infects the tree’s vascular system which then affects and/or stops the flow of water and nutrients within the tree.

 

How to Identify the Shot Hole Borer

Unfortunately, the beetles are the size of sesame seeds and can be hard to spot, however, you can identify an infected tree by looking for the following signs:

  • Wilting or missing leaves
  • Dead or dying Branches
  • Entry or Exit holes on the bark (the size of a pen tip) – these holes may have staining around them
  • Shotgun like lesions on the bark at entry or exit hole
  • Sugar Volcanoes on the bark at entry or exit hole
  • Blotches of oozing resin on the bark at entry or exit holes
  • Wood frass (wood powder) on the bark at entry or exit holes

 

What Can I do about PSHB?

The PSHB beetle drills very deeply into the wood, which is why no remedy has, as yet, been discovered for this pest. We recommend KOINOR at this stage, but results are, unfortunately, not guaranteed.

The public can also aid in the management of the spreading of this infestation by reporting any signs to FABI (Forestry and Biotechnology Institute).

The discovery of this beetle in South Africa is a major concern to foresters, farmers, tree fellers and landscapers as these beetles are very aggressive and are known as tree killers. We have a large biodiversity in South Africa hosting 299 species of mammals and 858 species of birds, all depending on trees for their food and shelter. It is our duty to take care of the natural beauty we are blessed with.