Latest News Archive

Please select Category, Year, and then Month to display items
Previous Archive
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

Plant-strengthening agent enhances natural ability of plants to survive
2015-07-27

Drought, diseases, and fungi. These are factors that farmers have no control over, and they often have to watch despondently as their crops are damaged. In addition, the practice of breeding plants in special and strictly-controlled conditions, has resulted in crops losing the chemical ability to protect themselves in nature.

Researchers in the Department of Soil, Crop, and Climate Sciences at the University of the Free State (UFS) have developed an organic agent that restores this chemical imbalance in plants. It enables the plant to build its own resistance against mild stress factors, and thus ensures increased growth and yield by the plant.

ComCat®, a plant-strengthening agent, is the result of extensive research by the German company, Agraforum AG, together with the UFS. Commercialisation was initially limited to Europe, while research was done at the UFS.

“Plants have become weak because they were grown specially and in isolation. They can’t protect themselves any longer,” says Dr Elmarie van der Watt from the department.

Dr Van der Watt says that, in nature, plants communicate by means of natural chemicals as part of their resistance mechanisms towards various stress conditions. These chemicals enable them to protect themselves against stress conditions, such as diseases and fungi (biotic conditions) or wind and droughts (abiotic conditions).

Most wild plant varieties are usually well-adapted to resist these stress factors. However, monoculture crops have lost this ability to a large extent.

The European researchers extracted these self-protection chemicals from wild plants, and made them available to the UFS for research and development.

“This important survival mechanism became dormant in monoculture crops. ComCat® wakes the plant up and says ‘Hey, you should start protecting yourself’.”

Research over the last few years has shown that the agent, applied mostly as a foliar spray, subsequently leads to better seedlings, as well as to growth, and yields enhancement of various crops. This is good news for the agricultural sector as it does not induce unwanted early vegetative growth that could jeopardise the final yield ? as happened in the past for nitrogen application at an early growth stage.

“The use of synthetic agents, such as fungicides which contain copper, are now banned. Nowadays, options for natural and organic agriculture is being investigated. This product is already widely used in Europe, but because farmers are often swamped by quacks, the South African market is still somewhat sceptical.”

We use cookies to make interactions with our websites and services easy and meaningful. To better understand how they are used, read more about the UFS cookie policy. By continuing to use this site you are giving us your consent to do this.

Accept