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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

UFS involved in project to light up the townships
2006-06-06

The parties involved with the project are from the left: Prof Hendrik Swart (Departmental Chairperson of the UFS Department of Physics), Dr Thembela Hillie (CSIR), Prof Neerich Revaprasadu (Department of Chemistry at the University of Zululand) and Dr Wynand Steyn (CSIR).

UFS involved in project that could light up the townships   

The University of the Free State’s (UFS) Department of Physics is involved with a project that could make life easier in the townships through the use of artificial light.

“The project is based on the use of sunlight to activate nano material in for example cement and paint during the day. At night the cement or paint can then radiate light,” said Prof Hendrik Swart, Departmental Chairperson of the UFS Department of Physics.

According to Prof Swart an amount of R3,9 million has been made available by the Council for Scientific and Industrial Research (CSIR) for the further development of the project.   

Prof Swart visited the University of Florida in America in 1995 for a year where he researched luminescent phosphor material that is suitable for flat panel television screens.  The red, green and blue spots on the television screens originate from these kinds of phosphor materials.  “At that stage plasma television screens were only a dream.  Today it is sold everywhere,” said Prof Swart. 

“Upon my return I started a research group at the UFS which investigated the degrading of phosphor material.  We also started to concentrate on the effectiveness of nano phosphors.  In the mean time our cooperation with the Americans was strengthened with follow-up visits to America of my colleagues, Prof Koos Terblans and Mr Martin Ntwaeaborwa,” said Prof Swart.

“Nano phosphors are basically luminescent powders that consist of particles that are 1 millionth of a millimetre.  These particles can provide light as soon as they are illuminated with, for instance, sunlight.  The amount of time these particles can provide light, is determined by the impurities in the material,” said Prof Swart.

According to Prof Swart nano particles are developed and linked to infrastructure materials in order for these materials to be excited during the day by sunlight and then it emits light during night time.

“The nano material is of such a nature that it can be mixed with materials, such as paint or cement. The yellow lines of roads can for example emit light in a natural way during night time,” said Prof Swart.

About a year ago Prof Swart and Dr Thembela Hillie, a former Ph D-student of the UFS Department of Physics, had discussions with Prof Neerich Revaprasadu from the University of Zululand and the CSIR about the possibility of mixing these nano phosphor particles with other materials that can be used as light sources in the building of roads and houses.

“Prof Revaprasadu is also actively involved in the research of nano materials.  Our efforts resulted in the CSIR approving the further extension of the project,” said Prof Swart.   

“The UFS and the University of Zululand are currently busy investigating ways to extend the light emitting time,” said Prof Swart.  

“There are eight M Sc and Ph D-students from the UFS and about five students from the University of Zululand working on this research project.  The Department of Physics at the Qwaqwa Campus of the UFS, with Francis Dejene as subject head, is also involved with the project,” said Prof Swart.

According to Prof Swart the further applications of nano materials are unlimited.  “Children whose parents cannot afford electricity can for instance leave any object such as a lamp, that is covered with these phosphor particles, in the sun during the day and use it at night as a light for study purposes,” said Prof Swart.

According to Prof Swart the further extension of the project will take about two years.  “During this time we want to determine how the effectiveness of the phosphors can be increased.  Discussions with the government and other role players for the possible implementation of the project are also part of our planning,” said Prof Swart.


Media release
Issued by: Lacea Loader
Media Representative
Tel:   (051) 401-2584
Cell:  083 645 2454
E-mail:  loaderl.stg@mail.uovs.ac.za
6 June 2006

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