Polyphagous Shot Hole Borer Beetle (euwallacea fornicatus)
The polyphagous shot hole borer (PSHB) beetle has been introduced into South Africa and it is spreading rapidly within the urban forests – millions of trees are projected to die.
Affected trees develop wilted brown leaves on infested branches. The most obvious sign of infestation is branches have brown stains around each hole where the borer has penetrated the tree.
Indigenous and exotic trees are attacked – the PSHB is generally indiscriminate since is does not eat wood, rather it feeds on fungus that it introduces into it’s host tree. The fungus (Fusarium euwallaceae) grows in the tunnels made by the borer – it is the fungus that kills the tree. Fusarium dieback occurs when your tree’s vascular system begins to fail, leaves begin to thin on the ends of branches, they turn brown, the branch and eventually the tree will die.
Boxelder, London Plane, English Oak, Chinese Maple are attacked particularly hard.
The distribution of established PSHB infestation in South Africa are Johannesburg, Durban, Richards Bay, Pietermaritzburg, George, Knysna and Hartwater.
Johannesburg with its dense urban forest has been hit part particularly hard.
FABI (Forestry & Agricultural Biotechnology Institute) within the University of Pretoria are extensively researching the PSHB here in South Africa. FABI has setup the following PSHB research portal.