The Northern Cape Department of Agriculture, Land Reform and Rural Development is concerned about the occurrence of a new pest that occurs on the pecan nut trees in the Vaalharts area. The Polyphagous Shot Hole Borer (PSHB) has a wide host range that includes important crop tree species such as orange, peach, grapevine, avocado, macadamia, pecan trees as well as forest trees such as the cabbage tree, monkey plum, common coral tree and honey flower.
A fungal pathogen, Fusarium euwallacea, is associated with the PSHB. This pathogen is a symbiont of this beetle (i.e. they live in close association) and can eventually kill an infested tree. The beetle bores into the wood, transmits 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. Currently the Department cannot confirm whether this beetle is transmitting the fungus to the pecan nut tree – more research is needed. If the fungus is indeed transmitted, it will cause probably a slow decline, rot and ultimate die-back of trees.
At this stage, the Department is only aware of the presence on pecan nuts in the Vaalharts Region, however farmers in other areas are advised to be on the look-out for it.
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”. (Source DAFF)
Mr Phemelo Manankong –External Communications Officer
@ 053 802 5622 or 066 303 8177