Local Government, Environmental Affairs and Development Planning
(a) How (i) severe and (ii) widespread are the infection of trees by the polyphagous shot borer beetle in the province, (b) what is being done to monitor actively the spread of these
beetles, (c) where would members of the public be able to access information regarding the presence of the beetles, (d) what does science tell us about their (i) references, (ii) ability to survive in dead wood, (iii) life cycle and (iv) resistance to insecticides and (e) what actions is his Department taking to address the potential damages caused by the shot borer beetle?
[a] [i] Severity: Polyphagous Shot Hole Borer [PSHB] is a slow onset infestation with tree deaths reaching their peak in the 5th year after discovery in an area. Scientists have concluded that 30% of urban trees are susceptible to PSHB, Cape Town for example has an estimated 4 million trees and could lose as many as 1 million trees to PSHB in the next decade. This could generate as much as 10 million decimal cubic meters [DCM] of infested green waste/firewood that requires handling and safe disposal. Only agricultural affected area in the province is the Helderberg, where PSHB has infested Avocado, Pear, and Plum orchards.
[ii] Current PSHB Distribution: Bitou [Greater Plettenberg Bay, Harkerville Forest]; George [George, Wilderness]; Knysna [Knysna, Sedgefield]; City of Cape Town [Somerset West]; Stellenbosch [Stellenbosch]. PSHB was discovered in Somerset West, Cape Town Cape in 2019, by 2022 an estimated 10 thousand trees had been infested with PSHB in the Helderberg. Recently it was confirmed to be present in the town of Stellenbosch, but the true extent of the distribution in the province is unknown.
[b] [i] The competency lies with the national Department of Agriculture, Land Reform and Rural Development [DALRRD] which promulgated control measures and convened Polyphagous Shot Hole Borer Steering Committee [PSHBSC] under the Plant Protectorate. The Department of Forestry, Fisheries, and the Environment [DFFE] plays a support role and is waiting for ministerial approval to have PSHB classified as a Neba 1b invasive pest.
[ii] In addition, trapping is currently undertaken by Stellenbosch University together with the Forestry Agricultural Biotechnology Institute [FABI] who are actively monitoring in Wilderness, Kirstenbosch and Helderberg areas. Kirstenbosch has had no interceptions to date.
[iii] The City of Cape Town’s Invasive Species Unit is coordinating monitoring and removal of infested trees 2019, with the Western Cape Disaster Management Centre forming part of the National PSHB Steering Committee.
[c] FABI, in collaboration with colleagues from several other Universities, are coordinating monitoring efforts and leading research on the PSHB and its fungus in South Africa.
They have developed an information hub on the following webpage: www.fabinet.up.ac.za/pshb, the purpose of which is to provide:
[i] Background information on the PSHB and its management to the public and all stake holders,
[ii] Updated information on its distribution and its host trees in South Africa.
[iii] Feedback on ongoing research and monitoring efforts by the PSHB Research Network, and
[iv] A platform for the public to make us aware of possible new host trees of PSHB and localities where it occurs.
Reporting:
[i] Reporting PSHB on CapeNature Nature Reserves to: pshb@capenature.co.za
[ii] Within the City of Cape Town municipal area via the online tool on: https://www.capetowninvasives.org.za/ ; and
[iii] Sightings in any other areas to be reported to FABI [Forestry and Agriculture Biotechnology Institute] at: https://www.fabinet.up.ac.za/ .
[d] [i] The preferences: PSHB is a concern for Pear, Plum, Avocado, Almond, and Pecan production in the province. In urban settings PSHB prefers English Oaks, Boxelders, Coral tree, London planes and many more:
https://www.fabinet.up.ac.za/images/PSHB/PSHB_host_list_2022-03-22_v2.pdf
[ii] Ability to survive in dead wood: PSHB infested dead wood is the primary vector for the spread of the pest/pathogen complex, however infested green waste that is not composted also poses a great risk. Plant material as small as 2,5cm can also be infested with PSHB.
[iii] Life cycles: PSHB spends 98% of their life cycle inside trees, this makes it very hard to manage. It is thought they will become naturalised.
[iv] Resistance to insecticides, of these beetles: There are no registered or safe insecticides to control PSHB South Africa [Act. 36/1947]. Stellenbosch University and FABI are investigating management strategies but have not published any data. No sexual aggregation pheromones are effective; therefore, removal of infested reproductive hosts trees is recommended.
[e] Same as answer b
