Why Should We Be Concerned?
Johannesburg is home to one of the world’s largest urban forests, but it’s come under threat from a tiny beetle. About 200 species of trees – many of them indigenous to South Africa – are afflicted with the pest and the fungus it carries. As scientists desperately look for a solution, many of the city’s trees are dying and experts are concerned the infestation could move from the forest to croplands next.
The PSHB along with its fungus has caused tremendous damage to the trees in the US, specifically California, in addition to regions in the Middle East. Moreover, the beetle has been recently discovered in Sandton, which is Johannesburg’s economic hub. This discovery is particularly concerning because Johannesburg is believed to be one of the world’s largest urban forests with over 10 million trees. Furthermore, judging by the number of trees the beetle has killed in Johannesburg as well as Knysna, this beetle could potentially be one of South Africa’s largest ecological tragedies. In addition, the beetle is currently infesting over 200 tree species from 28 plant families worldwide.
How does the beetle infest the tree? Actually, the beetle itself doesn’t kill the tree; rather it is the fungus that accompanies the beetle. The fungus targets the trees vascular system inhibiting the flow of water and nutrients within the tree.
How To Identify The Shot Hole Borer:
Unfortunately, the beetles are too small to detect. However, what you can do is identify the infected trees. The symptoms of infected trees vary from one tree species to another and there are many signs that show when a tree is infected. Some of these signs are:
- Wilting trees
- Dead branches
- Exit/Entry holes on the bark of the trees
- Shotgun-like lesions on the bark at entry/exit holes.
- Sugar volcanoes on the bark at entry/exit holes.
- Blotches of oozing resin on the bark at entry/exit holes.
- Wood frass (wooden powder) on the bark at entry/exit holes.
It was previously mentioned that the PSHB infects more than 200 tree species from 28 plant families. Therefore, it would be difficult to list all of the tree species. However, some of the important commercial crops you should know about that are susceptible to the Shot Hole Borer beetle are:
- Avocado (which suffered heavy damaged in California)
The Lower Houghton residents Association (LHRA) is arranging for an expert arborist to speak to us about the problem. He will help us identify infected trees and do a short walkabout in the suburb to demonstrate the effect of this infestation. He will also discuss treatment options.
When: Saturday, 23rd February
Venue: 19 Sixth Avenue Houghton Estate