‘A huge challenge is that municipalities are not equipped to deal with such outbreaks’
– Associate professor at the University of Pretoria’s Forestry and Agricultural Biotechnology Institute, Wilhelm de Beer, bemoaning local municipalities’ inability to control pest outbreaks such as the current shot hole borer infestations
South Africa’s porous borders and a lack of communication between government departments have made it difficult to restrict the spread of the East Asian polyphagous shot hole borer ( Euwallacea sp nr fornicates) in the country.
Wilhelm de Beer, an associate professor at the University of Pretoria’s Forestry and Agricultural Biotechnology Institute (FABI), told Farmer’s Weekly that the City of Cape Town, Johannesburg City Parks, the Stellenbosch Local Municipality, Kirstenbosch Gardens and the South African National Biodiversity Institute, as well as stakeholders in KwaZulu-Natal, were working on a strategy to stop the shot hole borer in its tracks if it arrived in areas in which it had not been previously found.
Commenting on the lack of control at South Africa’s borders, De Beer said officials that checked for these types of pests were only stationed at OR Tambo International Airport, and they were only on duty “during office hours”.
Farmer’s Weekly had previously reported that shot hole borer infestations had been discovered in pecan trees near Hartswater.
The insects transmitted the Fusarium euwallaceae fungus to the trees, which blocked the trees’ vascular tissue and thus impeded nutrient flow, resulting in branches dying back and the eventual death of the whole tree.
“The [stakeholders] are busy with an awareness campaign [for] municipalities, nurseries and those who sell firewood. Firewood is one of the biggest problems.
“We found a case in Johannesburg where someone bought firewood from an informal seller. This person [noticed that] the fruit trees in his garden were affected by an unknown bug.
“When we investigated, we found that a single piece of firewood of about 500g [contained] around 44 females, [each capable of laying] 1 400 eggs,” De Beer said. Studies in the US had found that even woodchips in mulch or compost that were smaller than 2cm in size could contain female insects, as about 5% of these females survived the mulching process.
Another problem occurred when trees bred in nurseries were infected, as the pest could then be spread across the entire country.
To date, shot hole borer infestations had been found in avocado, guava, plum and peach trees in domestic gardens, as well as grapevines, but thus far it only seemed to negatively affect commercial pecan nut trees, he said.
“A huge challenge is that municipalities are not equipped to deal with such outbreaks. There is also a large communication gap between municipalities and the department of agriculture, [among others]. But we are [in the process of ensuring that] lines of communication are opened,” he said. – Gerhard Uys