Posts Tagged ‘ shothole borer ’

Shothole Borer Beetle – an Ecological Tragedy Gogga of the Month Shot Hole Borer Beetle

Posted on: April 12th, 2021 by Cassidy No Comments

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!

 

How the shot hole borer operates

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.

 

What happens to our trees

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.

 

Identifying an infected tree

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:

  • Multiple round 1mm wide entry-holes, similar to paper punch holes.
  • Dark, wet staining, oozing, and thick gumming around suspicious holes.
  • Streaks of white powder, sugar volcanoes, or fine sawdust coming from trunk/branch holes.
  • Wilting trees and dead branches.
Best course of action

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,

  • Start a watering and fertilising regime for your trees to make them as healthy as possible to withstand an attack. If a tree is strong enough, it can flood borer tunnels with gum or sap.
  • Call in an arborist to advise if the tree is a valuable investment tree on your property.
  • Any dead wood infested with shot hole borer beatles should be covered with thick plastic before moving. The moving of infested firewood is one of the biggest pathways to spreading this invasive species. Chip and solarise infected wood on site.
  • Notify your neighbours and create awareness so that everyone is on board and informed.
  • Report infected trees here: clinic@fabi.up.ac.za

 

Did you know?
  • 300+ Trees have had to be removed in JHB North.
  • Shot hole borers love certain trees more and will always head to their favourite six species. This means that the most affected tree species are: London plane, Boxelder, Japanese and Chinese maple, English oak, and Liquidambar. Monitor these species closely in your garden and remove them as soon as branches begin to die.
  • These six trees are regarded as target species for the shot hole borer. Once the beetles have colonised these trees with thousands of offspring - and the trees begin dying - the shot hole borers spread to nearby trees which are then infested.
  • Country-wide surveys found that several fruit trees (including peach, olive, grapevine, guava, and fig) have been infested in urban areas.
  • Indigenous tree species such as coral trees, wild olives, yellowwoods, and Natal figs, are the most threatened.
  • Judging by the destruction in Knysna, as well as the rise of beetles in Sandton (one of the world’s largest urban forests with over 10 million trees), the shot hole could well be one of South Africa’s largest ecological tragedies of all time.
  • The shot hole is currently infesting over 200 tree species from 28 plant families.
  • These beetles are transported by humans through moving infested firewood – so burn or chip the wood and place it under plastic for six weeks in full sun (known as solarisation).   Never move infested wood unless it is under a thick plastic tarpaulin. Otherwise, beetles fly off the back of a bakkie and infest all properties along the route to a garden dump.

 

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.

Let’s save our trees! Shothole Borer

Posted on: February 18th, 2020 by Shahnee Stockigt No Comments

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.

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
  • Tiny, pen-tip sized holes randomly spaced in the bark
  • The holes may have stained marks around them, or have white sugary powder, (known a sugar volcanos), or even gummy beads oozing out of the holes, or most likely “sawdust” on the tree and below it on the ground.

To view images of infested trees: PSHB.co.za/pshb-tree-identification/

To view the beetles: PSHB.co.za/pshb-beetle-identification

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, (ask your local GCA Garden Centre for advice).
  • Introduce microbe stimulants to the soil around your trees to improve the soil and thereby the tree’s health and vigour, (again, ask advice from your local GCA Garden Centre).
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 – 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).

Be responsible:

Just one heavily infested tree may contain over 100,000 beetles, therefore we need to:

  1. Spread the word via social media and word-of-mouth to our neighbours and communities if we find infected trees, since the risk to healthy trees from those already infected is very high and the female beetle can fly up to 1 km infecting suitable surrounding trees.
  2. 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. Find excellent solutions at https://polyphagous-shot-hole-borer.co.za
  3. Sterilize any pruning equipment or wood-chipping equipment that comes into contact with infected wood.
  4. Do not transport wood or fire-wood from one area to another without being sure that it is not infected or has been treated.
  5. Be part of the solution by reporting infested trees. Go to jufa.org.za/pshb to acquire the information that you will need to email to pshb@fabi.up.ac.za. A Tree Survey app can also be downloaded from Google Play or iTunes. A user guide is available at TreeSurvey.co.za/how-to-guide/

For more gardening tips and information, visit www.lifeisagarden.co.za  or join the conversation on our Facebook page: www.facebook.com/lifeisagardensa.