Rising Sun: The Polyphagous Shot Hole Borer

My thanks to Mike Vink for posting a blog from the International Convention in Hamburg - at least it's not all schnapps, bockwurst und beer!

We were honoured by the presence of a number of guests at the meeting - Jacks Mokoka, Thoko Msibi, Claire Thorogood, Sarah Klipin, Tim Conradie and Antonette Grobler.

Antonette Grobler and Carin Holmes

This weeks speaker was Mike Viviers (email address growing@rhn.co.za) from Random Harvest Indigenous Nursery - an ecologist by training. Mike was accompanied by Tim Conradie, who also gave some input. The Polyphagous Shot Hole Borer, or PSHB for short, is having a catastrophic impact on our country's historic, exotic and indigenous trees.

Mike Viviers of Random Harvest Indigenous Nursery

Hailing from Southeast Asia, this pest was officially discovered in SA in 2017, in the Pietermaritzburg Botanical Gardens. Since then it has spread to every province except Limpopo. PSHB is an ambrosia beetle, about 2mm long, which tunnels in the wood of trees. The female beetles infest trees with a fungus - they feed on the fungus, not the wood - and it's this fungus that kills the trees in the end.

A polyphagous shot hole borer on a man's hand

Passionate about his subject, Mike gave a detailed and somewhat technical talk on the PSHB which is becoming a major crisis and could change the face of Africa. Government is yet to declare the infestation an emergency to our ecology and is taking a "wait and see" attitude.

It seems that there's no way to protect our trees against the beetle, but Mike and his team have been carrying out substantial work to find a way to counter the effects of the PSHB. These include the use of lipids (fats) using the beetle as a "trojan horse" to carry the lipids in the form of a fungus which develops and which eliminates the food source of the beetle. Mike and his team have developed a spray that is not harmful to man, and for the cost of R40 a tree will eliminate the spread of the beetle.

Obviously the cost and effort involved could be enormous, but Mike and his team are determined to tackle the scourge, one tree at a time.