Cape Town's 'PSHB ground zero' is Somerset West
On 9 April, 2019, the City of Cape Town confirmed that the invasive polyphagous shot hole borer (PSHB) beetle was positively identified in Somerset West.
The PSBH infestation was discovered in Oldenland Road, Somerset West by passionate gardeners and environmentalists who noted that a London plane tree in their garden was ailing and exhibited signs of a PSHB beetle invasion.
Phumudzo Ramabulana, the City of Cape Town’s Invasive Species Unit's PSHB expert, contacted - Elmar van Rooyen - a postgraduate at Stellenbosch University who is currently working on the PSHB beetle for his PhD thesis.
Assisted by arborist, Paul Barker, they collected samples from the infested sweetgum (Liquidambar styraciflua) and London plane trees in Oldenland Road for laboratory analyses.
On 3 April 2019 after extensive DNA testing the results of the positive PSHB identification were released in a statement by academic experts from the Stellenbosch University’s Department of Conservation Ecology and Entomology and the Forestry and Agricultural Biotechnology Institute at the University of Pretoria.
The City immediately embarked on a plan to remove the trees - noting that it was critical that the PSHB beetles were not spread during the removal project.
An experienced invasive plant removal team - from the Invasive Species Unit - trained in the dangers of vector pathways and cleaning equipment got to work.
The wood from the infected trees was chipped on site and machine fed into a large covered truck line with thick PVC plastic. The chips were carefully removed to a different site where they were incinerated.
Cape Town mobilises...
The news was greeted with dismay, after which Cape Town's green industries mobilised.
Over 170 landscapers, arborists, horticulturists, estate managers, growers and garden centres managers attended the invasive Polyphagous Shothole Borer Beetle (PSHB) industry Info Session & Workshop.
** Venue: Old Mutual Conference and Exhibition Centre at Kirstenbosch.
** Hosted: By the Cape Green Forum on Thursday 25 April 2019.
The country's top PSHB experts... Professor Wilhelm de Beer (FABI, University of Pretoria) and Prof Francois Roets (Stellenbosch University) gave an indepth address on the tree crisis created by the PSHB's South African invasion.
Chandre Rhoda (City of Cape Town - Invasive Species Unit), Altus de Wet (City of Cape Town - Arborist) and prominent Cape Town arborists, Francois Krige and Paul Barker gave their perspectives on how the war against the PSHB should be fought in Cape Town.
#PSHB #shotholeborer #invasivespecies #CapeTownInvasives #CapeGreenForum
Prof. Wilhelm de Beer & Prof. Francois Roets
Elmar van Rooyen & Phumudzo Ramabulana
Chandré Rhoda & Marijke Honig
Cape Town journalist, Karen Watkins reports...
Top journalist, Karen Watkins of the Constantiaberg Bulletin, attended the workshop...
This is her impression of the information ... as printed in the Independent Newspapers regional newspaper - https://www.constantiabergbulletin.co.za/news/invasive-beetle-threat-22352972
"It’s as tiny as a flea, but the polyphagous shot hole borer beetle is laying waste to forests of mighty trees around the world, and now it’s headed this way. It might already be in your garden", writes Watkins.
"The bug has been chewing away at Johannesburg’s green lungs, and scientists fear it could soon start doing the same here, not only changing city streetscapes but attacking fruit trees and threatening farms and nature reserves.
Last week, over 100 arborists, landscapers, retailers, growers, ecologists, compost and soil suppliers and Lourensford and Vergelegen wine estates met to discuss how best to ward off the beetle.
They urged Capetonians to check their trees and raise the alarm should they spot the beetle.
The shot hole has shown a preference for oaks, most willows, plane trees, avocado, some acacias and most maples, according to Altus de Wet of the City’s recreation and parks.
Marco Meyer, Apiwe Mhlawuli, Angelique Africa, Solulele Mhandana, Lietseko Magwagwa
City ISU: Mfundo Tafeni (2nd from left), Alvina Brand & Zikhona Sokudela (right).
Mashudu Phalanndwa (Invasive Species Unit) & Thandikhaya Kotyi (Recreation & Parks)
PSHB Academics Talk to Cape Town's Green Industries
Watkins writes, "According to professors Wilhelm de Beer and Francois Roets, most borer beetles live in dead wood, but this ambrosia beetle does not eat wood.
Instead, it burrows into living trees, establishing brood galleries where it lays its eggs. It introduces a fungus (fusarium euwallaceae) which becomes food for developing larvae and adult beetles.
This fungus blocks the water-conducting tissues of the tree and ultimately causes its death.
Professor De Beer said that by the time the beetles and fungus had killed a large tree, it could be home to thousands of beetles and when they emerged, the females could fly up to three kilometres and attack surrounding trees.
“They’re unstoppable, but good management can reduce the impact,” said Professor Roets.
“The beetle is sensitive to heat, therefore, the best method of eradication is to remove infested branches. Either burn these immediately or cut into smaller pieces, place in sealed refuse bags and leave in direct sunlight so the heat will kill the larvae and the insect,” he said.
Di Irish, with Norah de Wet & Redewaan Isaacs
Top designers: Ray Hudson & Clare Burgess
Thandikhaya Kotyi, Altus de Wet & Lawrence
City of Cape Town Invasive Species Unit shines
Other municipalities have been slow to introduce control measures. However, the City of Cape Town’s Invasive Species Unit has introduced a management protocol".
Programme manager Chandre Rhoda said they had received 80 sightings of which 21 affected trees had been removed.
“It’s critical that these beetles are not spread during removal. The project contains the biomass and treats tools used in the removal process. The wood is chipped onsite and incinerated,” said Ms Rhoda, adding that the City was creating awareness through Friends and hack groups.
Professor Roets said a further problem was that beetles could fly and can get into clothing, vehicles, and cut wood, increasing their spread.
Karen Watkins and Cherise Viljoen
SALI National Chairperson, Norah De Wet
Team Lourensford Estates
No registered solution for killing the PSHB beetle
Watkins writes: Large-scale chemical treatment was not an option, but could be used on high value, individual trees, said Professor de Beer.
An insecticide used in America is Imidacloprid, but it’s a prime chemical suspect blamed for bee-colony collapse, according to Mike Allsopp, from the honeybee research section of the Agricultural Research Council.
Professor De Beer said symptoms indicating the presence of this beetle vary from patches of white, powdery wood (frass) around the tree or on the trunk, blotches of oozing resin at the beetles’ entrance hole, and/or small raised lesions on the bark.
Professor De Wet said he was not overly concerned about vines as the bark was too dry for habitation by this beetle. “However, fruit trees and oaks are a far greater concern,” he said.
Dr Tony Rebelo said the beetle turned up in California in 2003 and Israel around 2008 and there were no reports of infestation in those wine producing areas.
Jean Naude, CEO of Groot Constantia, said according to VINPRO (a non-profit company representing 3 500 South African wine producers, cellars and industry stakeholders) the beetle has not yet been detected in South African vineyards.
Leslie Naidoo, Richard Arm and Clare Burgess..
Prof Wilhelm de Beer & Johan Smuts
Sivu Kweleta & Elmar (Meg) van Rooyen
Cape Town arborists offer their opinion
Watkins writes: Arborist Francois Krige, who cares for trees at Kirstenbosch and Platbos, encouraged companies to train their staff to be on the lookout for the beetle and to ensure cleanliness of equipment, such as chainsaws and vehicles.
Paul Barker, of the Friends of Arderne Gardens in Claremont, has a number of champion trees. He encouraged residents to join iNaturalist and keep up to date with information regarding the beetle.
Professor De Wet said everyone needed to take action to stop the beetle’s spread.
“People should go outside, look at your trees. If you find the beetle, report it. Put pressure on your local authorities to respond,” he said.
If you are a resident in the Cape Town Metro - report any sightings of the beetle to the reporting tool on the City's website - https://www.capetowninvasives.org.za/shot-hole-borer
Facebook Page: https://web.facebook.com/ctinvasives/
Download attachments: See pdf pages from the Constantiaberg Bulletin - 2 May 2019. Attachments are detailed just below the main title of this feature ... above.