Save your plants and trees from shot-hole borer
The trees the shot-hole borer infects include both indigenous and exotic species including some fruit trees such as avocados.
Gardens are under attack by an enemy that can barely be seen. Over 200 tree species are under attack by a small, nasty 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.
What to look out for:
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:
- Wilted leaves or shedding of leaves.
- Dead or dying branches.
- Small pen-tip sized holes randomly spaced in the bark.
- The holes may have stained marks around them, or have white sugary powder (known as sugar volcanos), or even gummy beads oozing out of the holes, or most likely “sawdust” on the tree and below it on the ground.
What can I do to protect my trees?
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:
- Mulching the tree’s root area.
- Water sufficiently.
- Add nutrients to your trees via fertilizers, composts and manures.
- Introduce microbe stimulants to the soil around your trees to improve the soil and thereby the tree’s health and vigour.
What can I do to save my infected trees?
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. A surfactant, which helps insecticides penetrate the tree bark and reach the beetles in their tunnels will hopefully be registered in South Africa soon.
Just one heavily infested tree may contain over 100,000 beetles, therefore we need to:
Be responsible:
- Spread the word via social media and word-of-mouth to neighbours and communities if you find infected trees, since the risk to healthy trees from those already infected is very high and the female beetle can fly up to one kilometre infecting suitable surrounding trees.
- Quickly dispose of infested trees parts or dead trees in a manner that prevents the beetle spreading further. Dead trees can remain as a breeding ground for up to a year.
- Sterilise any pruning equipment or wood-chipping equipment that comes into contact with infected wood.
- Do not transport wood or fire wood from one area to another without being sure that it is not infected or has been treated.
- Be part of the solution by reporting infested trees.
For more gardening tips and information, visit www.lifeisagarden.co.za or join the conversation on Facebook: lifeisagardensa.
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