Conservancy issues shot hole borer warning

Amanzimtoti Conservancy warns residents to be on the lookout for the troublesome polyphagous shot hole borer beetle (PSHB) which is causing widespread damage to the environment worldwide. No infestations have been reported locally, but the conservancy thought it best to get the warning out early.

“Unfortunately this little beggar has been imported into South Africa through a wood source which was not treated and certainly not identified at our borders,” said the conservancy’s Gill van Wyk. “This is testament to the great need for border control of products coming into the country. We now face the potential of many of our trees dying and often owners not realising what the problem is until the rest of his garden also disappears.”

The beetles, also known as Euwallacea fornicatus, are about 2mm long and are native to Southeast Asia. They were discovered during a routine study for diseases in the KZN Botanical Gardens in Pietermaritzburg in 2017. The PSHB shares a symbiotic relationship with the Fusarium euwallacea fungi, which is the beetle’s main source of food, and is the main cause associated with the wilting of trees.

It is believed this beetle could potentially be one of South Africa’s largest ecological tragedies judging by the number of trees it has also killed in Johannesburg and Knysna. It is currently infesting over 200 tree species from 28 plant families worldwide.

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Unfortunately, the beetles are too small to detect, but you can identify the trees it has infected. Some of these signs include wilting trees, dead branches, entry or exit holes on the tree’s bark, shotgun-like lesions on the bark at these holes, sugar volcanoes on the bark, blotches of oozing resin and wood frass (wooden powder) at the holes.

Some of the important commercial crops the beetle has already infected are the avocado, pecan, peach, orange and grapevine.

No remedy to stop the beetle has yet been discovered and insecticides have been found to be ineffective. The only way to combat them is to cut down and burn the affected wood to prevent their spread, and not to move plants that shows signs of being infected. Rather cut the tree into smaller pieces, keep it sealed and in direct sunlight to kill the beetle and its larvae.

Report any signs of infestations to the Forestry and Agricultural Biotechnology Institute in Pretoria.

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