Professor co-ordinating shot-hole-borer research discusses the necessary steps to control its spread
BRAAMFONTEIN – While the beetle's spread is unstoppable, with good management the impact can be reduced.
The South African Green Industry Council (Sagic) invited tree fellers, owners of nurseries, landscapers and others working in the green industry to a discussion held on 11 April at the Wits Club on how the nursery industry can help in preventing the spread of shot-hole borer.
The discussion was led by Professor Wilhelm de Beer from the Forestry and Agricultural Biotechnology Institute (Fabi) at the University of Pretoria. De Beer, who co-ordinates all research in the country related to the polyphagous shot-hole borer (PSHB), discussed the origin of this beetle and its impact in California and South Africa.
The beetle, which was most likely brought to South Africa on ships from Southeast Asia, has now been spotted in almost all of the provinces, with its greatest impact in urban areas.
De Beer sought to educate members of the green industry about how the beetle spreads. Methods include flying short distances, transportation of firewood, dumping of wood, fresh wood chips and nursery stock (including trees in bags with stems 2.5cm in diameter).
“Not all trees infested with the borer will die. This beetle is unstoppable, but with good management we can reduce its impact,” said De Beer.
He also suggested that highly infested reproductive host trees must be removed and disposed of at dedicated dumping sites, be solarised and chipped. This contradicts the current ruling from City Parks that only dead or dangerous street trees should be removed.
He also said that it is important to begin planting new, resistant trees to replace the lost treescape.
De Beer stated that government needs to roll out a national strategy on all levels to deal with the beetle, allocate budget to research and manage the borer, train staff, remove or treat reproductive host trees and designate dump sites for cut wood.
De Beer also raised the point that laws should be implemented to restrict the movement of firewood.
What remains unknown is the real risk posed by nursery stock and whether beetles are reproducing in this stock. He encouraged nursery owners to come forward and open up their sites for research.
“Nurseries are excellent sites for research regarding host species and resistant trees, propagating resistant trees and informing landscapers and the public about which trees would be best to plant,” concluded De Beer.
Details: info@sagic.co.za
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