Public urged to report any sign of deadly tree beetle

SANParks has called on members of the public to report any possible infestation by the invasive polyphagous shot hole borer beetles spotted in the Tsitsikamma Forest.

SANParks spokesperson Nandi Mgwadlamba said this week the organisation’s forest ecologists in the Garden Route National Park were breathing a sigh of relief as early observations showed the polyphagous shot hole borer (PSHB) was still absent in most parts of SA’s famous indigenous forest.

“But this does not mean we should not be on the lookout for this pest.”

The shot hole borer beetle did not kill a tree directly but rather left a fungus inside the infested tree’s circulatory system that effectively blocked nutrients and water, she said.

“This leads to branch dieback and ultimately the tree’s death.”

Mgwadlamba said Professor Francois Roets, from Stellenbosch University, had surveyed sites inside and outside the Garden Route National Park.

He had also been to the George Botanical Gardens and Knysna Pledge Nature Reserve – where the presence of the borer beetle in several tree species was confirmed – and to Forever Resort and Kat Rivier.

SANParks forest ecologist Graham Durrheim said following these visits it was clear that PSHB was still absent from several important sites.

“We can confirm it is absent at the Tsitsikamma Big Tree, Diepwalle, Storms River, Nature’s Valley and Garden of Eden,” he said.

Originally from southeast Asia, the polyphagous shot hole borer – so named because of the spray of holes like from the blast of a shotgun that it leaves in the trunk of infected trees – has wreaked havoc in urban and rural forests and plantations around the world.

In SA, it first showed up in the KwaZulu-Natal Botanical Gardens in Pietermaritzburg in 2017 and investigation showed it probably made its entry into SA through infected transport pallets missed by port control.

Durrheim said despite PSHB’s signature shotgun scatter of holes, identifying it conclusively was difficult.

“It is possible that several of the reports in other areas in the Garden Route could be of indigenous borer beetle species.”

PSHB infestations were most likely to be found at sites that were accessible to the public, particularly where they could have been introduced by infested firewood – in spots such as picnic sites, rest camps and along access roads, he said.

“Members of the public on the Garden Route are requested to report possible infestations to SANParks,” he said.

Queries should be e-mailed to graham.durrheim@sanparks.org or jessica.hayes@sanparks.org