A dreaded alien invasive bug that is killing trees all over the world is starting to make its grim presence felt in Gqeberha.
Horticulturist and leading local authority on polyphagus shot hole borer (PSHB), Chris Hay, said the beetle had spread widely in Gqeberha since a single confirmed identification two years ago — downing elms in Miramar, oaks in Framesby and Sunridge, and a swathe of the city’s much-loved coral trees in Walmer.
He said SA had its own shot borer which local trees had learnt to live with but the difference with PSHB was the fungus Fusarium euvallaceae it brought with it, that killed the tree rather than the beetle itself.
“The beetle lays eggs in the holes it bores and the larvae that emerge feed on this fungus, which is laid out ready for them like a veggie garden.
“The problem is the Fusarium blocks up the vascular system of the tree and it can no longer transport water and nutrients through its system.
“The top of the tree starts dying back and then eventually the whole tree dies.”
He said the infection spread when an impregnated female PSHB carrying Fusarium flew to a new tree and tunnelled into it.
The insect can only fly 500m to 1km but could reach much further if it was carried on the wind.
“The tree will try to heal itself and a tell-tale sign of this, depending on the species, is resin staining around the holes.
“But the fightback is normally fruitless, and in almost all cases the tree will succumb.”
Originally from Southeast Asia, PSHB is black or brown and about 1mm long with grey hairs.
The little beetle and the crippling padkos it carries with it have wreaked havoc around the world in indigenous forests and plantations from Israel to California.
It arrived in SA in 2017 in a contaminated cargo of crates and pallets and made its first confirmed appearance in KwaZulu-Natal in 2017.
In mid-2019, Hay warned of its imminent arrival in the Bay and in mid-2024 the metro parks department confirmed a dead tree on a Lorraine verge had been killed by PSHB.
Polyphagus refers to its capacity to eat a wide variety of trees and “shot hole borer” to the spray of holes as from a shotgun blast that scars the trunk of an infected tree.
Gqeberha-based veteran outdoor maintenance specialist Dave Allen said the situation was bleak.
“The main victims I see are common white and amber oaks, as well as yellowwoods, and the centre of the storm is Circular Drive through Charlo down to Dodd’s Farm.
“People call me to ask why their tree is dying and I go around to have a look, and this is what I find.”
He said the beetle was like a tiny alien arboreal aardvark and the sawdust was the earth that it kicked back out the holes as it tunnelled into the trunk.
“We are going to lose so many historic landmarks in areas like Park Drive, Mill Park and Hallack Road.
“You can plant another tree but you can’t replace 100 years of living heritage.”
Hay said the only two ways to possibly halt the spread of PSHB was to chip the infected wood into pieces smaller than 2.5cm or to burn it on site or transport it under tarpaulin to another controlled burning site.
Anyone wishing to confirm if a tree definitely has PSHB or not can call Hay at 083-793-9580 or metro official Busi Vezile at 066-217-9206.
Questions were sent to metro spokesperson Sithembiso Soyaya on Monday morning but no response had been received by the time of publication.
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