The Department of Agriculture, Forestry and Fisheries wishes to inform the farming community and members of the public about the detection of a new pest of concern Euwallacea sp. nr fornicatus, commonly known as the Polyphagous Shot Hole Borer (PSHB) that affects ornamental, indigenous and urban forest trees.
This pest was detected in South Africa for the first time in 2017, in Pietermaritzburg (Botanical Gardens), KwaZulu-Natal province, by the Forestry and Agricultural Biotechnology Institute (FABI) of the University of Pretoria. It was detected again in early 2018 in Gauteng province near the Sandton suburb of Johannesburg. There are also reports of infestation on pecan trees in Hartswater, Northern Cape province. The department has since established a working committee with other relevant stakeholders to do more research on the pest on how it can be effectively controlled and/or managed.
The Polyphagous Shot Hole Borer has a wide host range that includes important crop tree species such as avocado, macadamia, peach, orange, grapevine and pecan trees, as well as forest trees such as the cabbage tree, monkey plum, common coral tree and honey flower. The PSHB is associated with a fungal pathogen species, Fusarium euwallacea. This pathogen is a symbiont of this beetle (i.e. they live in close association) and can eventually kill an infested tree. The pest bores into the wood, transmitting the fungal pathogen in the process and the entire tree may die because of the fungal rot. The PSHB is a tiny beetle of about 2, 0 to 2, 8 mm long in size. Matured females are very dark brown to black in colour and are larger than their male counterparts.
Chemical control (injecting infested trees with fungicides and insecticides) may prove to be effective to control this tiny beetle and its fungus, but may be expensive. Plant materials showing similar symptoms, or infested trees, should be reported to the relevant authorities or alternatively cut down and chipped. In terms of the Sub-control measure 7(2) of the Control Measures R. 110 of 27 January 1984 as amended, “Any individual or organisation or institution that has for the first time identified or recorded a new pest to be present in the Republic, shall immediately report it to the relevant executive officer”.