More Polyphagous Shot Hole Borer (PSHB) beetle infestations have been discovered in Cape Town as concerns continue to mount.
Also read: City warns of invasive borer beetle spotted in Newlands
Following the sighting of the tree-killing beetle in Newlands last week, more of the city’s suburbs have been affected, particularly Rosebank and Mowbray.
Prior to last week’s discovery in the Southern Suburbs, only trees in Somerset West had been infested.
However, 12 locations have been recorded as affected since Sunday, causing a great deal of concern for the city.
During an inspection of the affected trees yesterday, chairperson of the mayoral advisory committee for water quality, Alex Lansdowne, confirmed the PSHB had entered the second stage of its colonisation, adding that the PSHB was always going to spread to the heavily vegetated southern suburb. The job now is to work together to track and manage the spread.
Last 2022, Local Government MEC Anton Bredell stated that scientists had found that about 30% of urban trees were susceptible to PSHB and that that the city can expect to lose as many as a million of its estimated four million trees over the next decade.
Parkscape and other environmental organisations have advised that four boxelder trees in Rosebank, near the Liesbeek River, were also carrying the very destructive beetle.
“The Liesbeek River has been identified as a priority pathway, more resources were allocated to conduct assessments to determine the extent and distribution of the beetle in the area,” said deputy mayor and Spatial Planning and Environment Mayco member Eddie Andrews, following assessments of the situation.
“The City will soon commence with the removal of the trees on City-owned land that are infested with the PSHB (on public open spaces, river corridors, green belts, road verges, public parks and so forth)”.
“Unfortunately, the only way to prevent the spreading of the invasive beetle is to chip affected trees, and carefully remove the biomass under cover of heavy duty plastic and to incinerate it at an appropriate site… We request residents to report sightings to the City as soon as possible.”
Meanwhile, conservation ecology and entomology professor at Stellenbosch University, Francois Roets explained that the beetle bores into the vascular tissues of trees and introduces a fungus that it feeds on. “It uses the living tree as a place to cultivate its fungal ‘crop’,” he explained.
“Damaging of the vascular tissues by the beetle and blocking of vessels by fungal growth reduces the ability of the plant to transport water and nutrients from the roots.”
“If there are enough infestations the plant simply cannot transport enough water and the tree usually then dies fairly rapidly with symptoms that are similar to those when trees are stressed by drought.”
“Boxelder trees can die in as little as a year and the first English oaks will likely start dying off within four years of initial infestation,” Roets said.
Also read:
Tiny beetle set to cost South Africa R275 billion if spread is not halted
Picture: Cape{town}Etc Library