Estate Living Magazine Investment - Issue 34 October 2018 | Page 44

HORRIBLE THINGS
COME IN SMALL PACKAGES
Joburg is being eaten by aliens, and we should be
panicking but we’re not. At least, not yet.
A silent, subtle threat to biodiversity is spreading across the country wood. Then, when the bugs lay their eggs, they (the adults) have
almost unnoticed – and this isn’t something removed from us in the a feast on the fungus’s rich crop of denatured wood – as do their
way of, say, rhino poaching that’s happening in the wilderness areas developing larvae once they’ve been hatched.
we visit only occasionally. It’s hitting us in our gardens and our cities.
It’s killing our trees, and it’s chomping its way through one of the The fungus, of course, clogs the trees’ food and water channels –
world’s biggest urban forests – Johannesburg. and the combination of burrowing and clogging does to the tree
what cholesterol in our bloodstreams does to us humans. It’s not a
We’ve known about the teeny-tiny (smaller than a match-head)
polyphagous shot hole borer (PSHB) beetle here in Knysna for some
pretty picture.
years. It attacked all the oak trees – many of which were planted All trees?
back in the Victorian era – that shaded the older streets and homes. No. Not all of them, but FABI has recorded shot hole borer beetles in
The municipality was forced to fell them, because they’d become around 60 tree species in South Africa – including oaks and planes,
so soft and spongy that they could fall over at any time and possibly but also in indigenous species like yellowwoods, coral trees, river
damage property or worse, injure or kill someone. bushwillows, thorn trees, tree fuchsias, indigenous willows, Cape
chestnuts, bush tickberry, keurboom, and others. It’s not only in
We thought they were specific to our oaks, but they’re not. After our front yards, either. FABI reports: ‘Some of these observations
scientists from the Forestry and Agricultural Biotechnology Institute come from semi-natural areas including the Garden Route Botanical
(FABI) found the bug in the iconic avenue of London plane trees at Gardens in George, and the Pledge Nature Reserve in Knysna.’
the KwaZulu-Natal National Botanical Gardens in Pietermaritzburg,
they systematically surveyed the trees in all South Africa’s botanical Nor is it a problem only in South Africa. It’s been recorded in
gardens – and found that ‘it has become alarmingly apparent that places as diverse as Israel and California, where it’s been found
PSHB is well established, thus has more than likely been present in on commercially important crops like avocados. Shock! Horror!
South Africa for some years. FABI believes this pest presents a very Imagine a world without avos!
serious threat to the health of trees in urban, agricultural and natural
environments.’
How does it affect the trees?
It’s important to understand that the bug alone isn’t the problem.
The adult female beetles farm the fungus, Fusarium euwallaceae,
which they carry with them wherever they go. While the beetles
burrow into the trees to establish brood galleries for their eggs, the
fungus colonises the gallery walls, and begins working away at the
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