Symptoms ?
By now you ’ re probably out in your prize-wining garden , staring at your trees . What are you looking for ? Tiny entry and exit holes in the bark ( think less than half the thickness of a matchstick ), which are usually surrounded by sawdust , and bleeding ( nectar or blobs of goo oozing from the bark ) are usually your first clues . But since the combination of boring and fungus weakens the core of the tree , branches may snap off , revealing the beetles ’ galleries and the webs of the black fungus that lines them .
How does it spread ?
Speaking to a group of environmentalists during a visit to Knysna earlier this year , FABI ’ s Prof . Wilhelm de Beer , a mycologist and fungal biologist , said that the beetle , which comes from Southeast Asia , was probably spread around the world in untreated timber such as that used for making shipping pallets .
Once here , though , the beetle can spread through the movement of infested branches – taking your diseased wood to the municipal dump , for example – or through the movement of infested nursery plants . FABI ’ s website notes : ‘ We have recently observed PSHB attacking containerised trees in the nursery environment . The potential for spreading over long distances through the sale and movement of nursery stock is cause for serious concern .’
So what ’ s being done about this ?
We ’ ve known for some time that increases in the movement of plants and plant material around the world are potentially huge threats to our biodiversity , which is why scientists have established the International Plant Sentinel Network which , according to its website , is
being developed to facilitate collaboration among institutes around the world , with a focus on linking botanic gardens and arboreta , national plant protection organisations ( NPPOs ) and plant health scientists . The aim will be for these institutes to work together in order to provide an early warning system of new and emerging pest and pathogen risks .
And , since our South African institutions are joining up as members , this means that we ’ ll be able to access the latest science on the subject . But the crucial words here are ‘ will be ’. We ’ re only at the start of our journey .
That said , however , here at home , the Department of Agriculture , Forestry and Fisheries , the Department of Environmental Affairs and various other stakeholders have formed a steering committee to develop an action plan for combatting the problem , to conduct surveys and monitor the spread of the problem , to plan and conduct trials on chemical treatments , and to create an awareness campaign ( especially to stop the movement of infested plant material – dead or alive ).
What can you do ?
Prof . de Beer noted in his talk in Knysna that control requires cutting down and removing infected plants , and the establishment of dedicated dumping sites where infected wood can be burned , fumigated or solarised . The latter is the simple but surprisingly effective strategy of sealing the infected plant material in plastic bags and leaving them in the sun to heat up . He said , too , that it is possible to treat economically valuable trees , or historically or culturally important specimens , with fungicides and pesticides , but none have yet been registered for this particular problem in South Africa .
Some people believe that the beetles could be lured and trapped , but this will only become possible when we fully understand their life cycle and breeding seasons , so that we can plan our campaign for the right time of year . And , anyway , it might not work . Insects communicate very effectively through pheromones , so they may be able to tell each other to stay away from our bug traps .
Prof . de Beer concluded his talk by telling us that the most efficient and long-lasting solution is likely to come from biological control , but that finding the correct one would cost millions , and could take years .
But given that we might lose enormous swathes of our urban and indigenous forests , which are some of our most important buffers against climate change and also add enormous value to properties around the country , perhaps now ’ s the time for government , individuals and private enterprise to start finding the funds to resource FABI to do just that . Which would truly be a good way to panic . www . servest . co . za
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