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26 September 2019 | Story Leonie Bolleurs | Photo Leonie Bolleurs
Read More Prof Wijnand Swart PSHB
A small 2 mm beetle, known as the Polyphagous shothole borer (PSHB) kills and infects trees. South Africa is the largest geographical area in the world to be infested with this tree killer. Pictured here is Prof Wijnand Swart who is working with two neighbourhood associations in Bloemfontein to monitor the occurrence of the beetle in the city.

Ornamental trees are dying all over South Africa, and it is feared that certain fruit and nut trees are also in danger. This is cause for great concern, not only among ecologists, farmers, foresters, and landscapers, but for homeowners as well. In private gardens and on streets throughout the country, trees that are afflicted include English oak, Chinese and Japanese maples, boxelder, and sweetgum.
 
The cause of all this havoc is a small 2-mm beetle, known as the Polyphgous shothole borer (PSHB; Euwallacea fornicatus) that originates from Southeast Asia.

Working to find a solution

"Based on damage seen in the USA and Israel, there is significant danger of losing many of our ornamental trees as well as fruit and certain nut trees in South Africa,” says Prof Wijnand Swart, Professor of Plant Pathology and Discipline Head in the Department of Plant Pathology at the University of the Free State (UFS).

Cases of afflicted trees were reported from all provinces in South Africa, except for Mpumalanga. Countries such as Israel and the USA have also suffered great losses as a result of this beetle.  

Research is being conducted on the beetle and its associated fungus, Fusarium euwallaceae, in order to understand their relationship and hopefully find a solution to stop, or at least manage, the invasion of trees. To investigate the largest geographical outbreak of this beetle in the world, academics from seven universities in South Africa are working together with the Forestry and Agricultural Biotechnology Institute (FABI) at the University of Pretoria through a multi-institutional and multi-disciplinary research network. UFS researchers are part of this network.
 
Senior Lecturer in the UFS Department of Plant Sciences, Dr Gert Marais, is conducting research on the PSHB and its associated fungi, with the focus on pecan trees, in conjunction with the South African Pecan Nut Producers' Association. Cases of infected pecan-nut trees were reported in the Northern Cape as well as in Nelspruit. 
 
Prof Swart is working with entomologists in the UFS Department of Zoology and Entomology to find a biological control agent to parasitise the beetle. “I have already found one instance of a parasitic wasp associated with the beetle and will continue to search for more specimens during the coming summer,” he commented. 
 
Understanding the beetle

The first cases of infected trees were discovered in 2017 when Dr Trudi Paap, associated with FABI and the South African National Biodiversity Institute, conducted a survey of pests and diseases in and around National Botanical Gardens in South Africa. 
 
FABI has been studying the tree killer intensively to find out more about its life cycle. The term ‘polyphagous’ refers to the ability of the PSHB to infest many different tree species.

On their website, FABI states that an important distinction is being made between different types of infestations. “Reproductive host trees are trees that are infested by the beetle and where it successfully establishes a breeding gallery in which the fungus grows, where eggs are laid, and larvae develop into mature adults, thus completing its life cycle. The majority of reproductive hosts eventually succumb to the disease symptoms caused by the fungus.”
 
“Non-reproductive host trees are trees where the beetle attacks, penetrates, and inoculates the fungus, which then starts to grow in the sapwood. However, the beetle either leaves or dies without reproducing in these trees. The fungus can eventually kill or damage reproductive hosts, but many of the tree species on this list seem to be unaffected.”
 
Involving the community

The situation also provides an opportunity for communities to directly benefit from research conducted by tertiary institutions. Prof Swart is working together with two neighbourhood associations in Bloemfontein to monitor the occurrence of the beetle in the city and surrounding areas. 

He urges residents in the Mangaung Metro who find instances of infected trees, to report it to Duart Hugo (duarthugo99@gmail.com ), who is compiling a database of infected trees in the area. 
 
FABI advises homeowners to cut down heavily infested reproductive host trees. Should you decide to burn the wood, note that beetles will fly away when the wood becomes hot or when smoke appears. Do not burn infested trees in uninfected areas.

Other interesting material

News Archive

DF Malherbe Memorial Lecture
2005-05-19

DF Malherbe Memorial Lecture: Language and language activism in a time of transformation (summary)
Proff Hennie van Coller and Jaap Steyn

Language activism necessary for multilingualism
The awareness is growing that language activism will be needed to bring about a truly democratic multi-lingual society. What is quite clear is that a firm resolve must continuously resist the concentrated pressure on Afrikaans-medium schools (and universities) to allow themselves to be anglicised through becoming first parallel medium, then dual medium, and finally English medium institutions.

Proff Hennie van Coller and Jaap Steyn said this last night (Wednesday night) in the 24th DF Malherbe Memorial Lecture at the University of the Free State. Prof van Coller is head of the Department Afrikaans, Dutch, German and French at the UFS. Both are widely honoured for their contributions to Afrikaans and the promotion of Afrikaans.

They discussed three periods of transformation since 1902, and said about the current phase, which started in 1994:  “Besides all institutions and councils having to be representative of South Africa’s racial composition, places of education were required to open their doors. Quite rapidly this policy has had the result that schools and universities may be solely English medium, but not solely Afrikaans medium. Afrikaans medium institutions — if they claim the right to remain Afrikaans — are quickly branded racist, even though their student body may include all races.

“Education departments are presently exerting great pressure on Afrikaans medium schools to become double or parallel medium schools.  Parallel medium education is an equitable solution provided it can be sustained. Established parallel medium schools, such as Grey College in Bloemfontein, have catered even-handedly for English and Afrikaans speakers for decades. But the situation is different in the parallel medium (and still worse in the double medium) schools that spring up usually at the behest of a department of education.

“Afrikaans schools are converted almost over-night into parallel or dual medium schools without any additional personnel being provided. Depending on the social environment, a parallel medium school becomes reconstituted as a dual medium school on average in five to eight years, and dual medium school becomes an English-only school in two to three years. Some Afrikaans medium schools have become English medium in just three years.

“Though the Constitution recognises mono-lingual schools, officials in the provinces insist that Afrikaans schools become dual or parallel medium; English medium schools are left undisturbed. One must conclude that the tacit aim of the state is English as the sole official language, despite the lip-service paid to multi-lingualism, and the optimistic references to post-apartheid South Africa as a ‘rainbow’ nation.”

They said a recent study has shown that the 1 396 Afrikaans schools in the six provinces in 1993 have dwindled to 844. The fall off in the Free State is from 153 to 97; in the Western Cape from 759 to 564; in Gauteng from 274 to 155; in Mapumalanga from 90 to 3; in the North West from 82 to 13; and in Limpopo Province from 38 to 12.

They said the changes at universities, too, have been severe, as university staffs well know. Ten years ago there were five Afrikaans universities. Today there are none. The government demanded that all universities be open to all, which has meant that all universities have had to become English medium. And no additional funding was forthcoming for the changes. The government policy amounts to a language “tax” imposed on the Afrikaans community for using Afrikaans.

“Only when all schools (and universities) are English will the clamor cease. Academics and educationists are beginning to speak openly of forming pressure groups to save Afrikaans schools, and of using litigation as one of their methods. 59% of Afrikaans parents have said they would support strong action if Afrikaans were no longer a medium of instruction at schools.”

 

 


 

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