Life is a Garden has some essential information to share this month. The shot hole borer beetle, known also as Euwallacea fornicates, is a huge threat to South African biodiversity and our gardens are certainly no exception. From the 80 species of trees under attack, 20 of these are reproductive hosts for this most gagga gogga, and with so many trees in SA and in private gardens, the threat is closer to home than we may think. Here’s some must-know info to help save our trees!
This invasive bugger from Asia is black in colour and smaller than a sesame seed (about 2mm long). Shot hole beetles dig tunnels in the trunks and branches of host trees where they then lay their eggs. The female beetle carries a fungus (Fusarium euwallaceae), which she spreads through these tunnels, which then becomes food for both larvae and adults.
The fungus spread inside tunnels completely disrupts the flow of water and nutrients of trees. Simply put, infected trees begin to die from the inside as the larvae hatch, digging through what’s left of the tree, and spreading more deadly fungus that causes trees to basically die from malnutrition. These beetles move a kilometre per week, rapidly infesting and reproducing.
Look out for signs of possible infestations by inspecting the trunks and branches of your trees and those in the surrounding area. Symptoms may vary across tree species, but here are the tell-tale indicators to take note of:
Sadly, there is no known insecticide that is effective against the Shot Hole as they drill so deeply into the wood. We can only be proactive by preventing the spread of the beetle and removing the environment that allows them to reproduce. In other words,
Our country is one of the world’s largest biodiversity capitals and host to 299+ species of mammals and 858+ species of birds. These animals depend on our trees as a source of food and shelter. Check if you have any of the six targeted tree species in your garden and keep monitoring them closely.
Gardens are under attack by an enemy that we can barely see. Arm yourselves with this valuable information and be ready to go to war!
Over 200 tree species are under attack by a tiny, nasty little tree killing borer beetle with a mouthful for a name; polyphagus shot-hole borer beetle, (or PSHB). The beetle, which is only the size of a sesame seed, creates tunnels deep into the tree where it reproduces and infect the tree with a fungus which in turn becomes the beetles’ food source as it eats the fungus. This fungus grows from the tunnels into the tree, harming it and can kill full grown untreated trees within a few seasons. The trees it infects include both indigenous and exotic species including some fruit trees such as avocados.
Since the shot-hole borer is so small and often not seen, it is easier to look for signs of infestation. The symptoms vary from one tree species to the next:
To view images of infested trees: PSHB.co.za/pshb-tree-identification/
To view the beetles: PSHB.co.za/pshb-beetle-identification
The good news is that not every tree will be suitable as a host for the beetle. Strong, healthy trees are less likely to be attacked and if infested, will withstand an attack better. You can boost the health of your trees by:
A fungicide has been developed that will eradicate the fungus, save the life of the tree and starve the beetle of food, often killing it too – enquire at your local GCA Garden Centre. (A surfactant, which helps insecticides penetrate the tree bark and reach the beetles in their tunnels will hopefully be registered in South Africa soon. To keep abreast of these developments, check for up-dates on the various PSHB websites).
Just one heavily infested tree may contain over 100,000 beetles, therefore we need to:
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