Will our oak trees survive borer beetle?
The warning signs on the oak trees in Meade Street - cautioning pedestrians to watch out for falling branches - are a stark reminder that the trees are under severe threat of the polyphagous shot hole borer (PSHB). The tiny 2mm ambrosia beetle has been sowing destruction in Israel and the United States and now our South African trees are faced with a similar threat.
Many of these landmark oaks are currently sprouting green leaves, but experts say that their spring growth does not necessarily mean they will survive the infestation of PSHB beetle.
An expert from the Forestry and Agricultural Biotechnology Institute (Fabi), Professor Wilhelm de Beer, visited George in April to examine our trees and an official DNA sample test result is still being awaited.
The borer beetle is not as active in winter as in summer but in warmer temperatures, the insect with its deadly fungal symbiont (Fusarium euwallaceae) emerges as a destructive invasive pest killing avocado and other trees in Israel and the United States.
A local landscaper said she was expecting commercial farmers to take active steps to protect their crops. However, upon enquiry, local fruit farmers did not reveal whether they have detected an infestation on their farms. Fabi has made an appeal to gardeners to watch out for the beetles.
Verdict out on fruit and nut trees
Operations manager of Macadamias
South Africa NPC, Barry Christie, said, “The macadamia industry is not affected yet, although it is very possible. The pecan industry is affected though. Fabi is working on a fact sheet to communicate to our industry, to make our members aware of the insect (for identification purposes) and symptoms. The next steering committee meeting is on 16 August in Pretoria to discuss the action plan forward. In the Southern Cape there are (fruit) farms from Riversdale to Pletttenberg Bay. Apparently some recent research in the USA indicated that as long as certain preferred host plants are destroyed, the insect populations decline. However, in South Africa I believe it will be difficult since some of the host plants are not that easy to eradicate and a conflict of interest might occur, as some host plants are farming crops.”
What the public can do
The public can contribute to the factfinding mission. Fabi has made an appeal to gardeners to watch out for the beetles. Details including photographs of the symptoms, GPS coordinates or a street address, the host tree species and the reporter’s contact details can be sent to diagnostic.clinic@fabi.up.ac.za.
The public was asked not to spread the