Free tool
What's Wrong With My Tree? Tree Disease and Pest Identifier
Answer two quick questions about what you can see, and find the most likely pest or disease for trees in South East Queensland, with a guide to what it means and how to treat it.
Step 1 of 2
Where is the problem?
Step 2 of 2
What do you see?
Most likely
Sooty mouldBest match
A black fungus growing on insect honeydew; it rubs off · likelihood ~15%
Scale insects
The insects usually behind the honeydew · likelihood ~15%
Most likely
Powdery mildewBest match
A white fungus on the leaf surface; it rubs off · likelihood ~5%
Most likely
Myrtle rustBest match
Egg-yellow spots on new growth of lilly pilly and other Myrtaceae · likelihood ~8%
Frangipani rust
Orange spots under the leaves of frangipanis only · likelihood ~5%
Most likely
Scale insectsBest match
Honeydew from sap-sucking insects, farmed by ants · likelihood ~15%
Sooty mould
Grows on the honeydew as it builds up · likelihood ~15%
Most likely
Scale insectsBest match
Waxy domes or shells that do not move · likelihood ~15%
Most likely
Psyllids and lerpsBest match
Sap-sucking psyllids under protective lerp covers · likelihood ~15%
Most likely
MealybugsBest match
Soft insects covered in white wax, often with egg sacs · likelihood ~5%
Scale insects
Cottony cushion scale, with a large fluted egg sac · likelihood ~15%
Most likely
Winter bronzing bugBest match
Tiny sap-sucking bugs; mature leaves bronze from May to September · likelihood <1%
Caterpillars: cup moth, processionary
Gumleaf skeletoniser, if the leaves are grazed to the veins · likelihood ~5%
Most likely
Psyllids and lerpsBest match
The lilly pilly psyllid, feeding in the soft new leaves · likelihood ~15%
Most likely
Galls (wasp, psyllid, mite)Best match
Galls the tree grows around gall wasps, midges or mites · likelihood ~5%
Most likely
Galls (wasp, psyllid, mite)Best match
Leaf galls made by thrips on Hills and Indian laurel figs · likelihood ~5%
Most likely
AnthracnoseBest match
A fungus spread by rain; worst in wet weather at flowering · likelihood ~3%
Most likely
Bronze orange bugBest match
Sap-sucking shield bugs that squirt a burning fluid · likelihood ~3%
Most likely
Possum damageBest match
Brushtail or ringtail possums feeding at night · likelihood <1%
Most likely
Caterpillars: cup moth, processionaryBest match
Leaves eaten back or grazed to the veins, often with larvae nearby · likelihood ~5%
Leaf beetles, incl. Christmas beetles
Scalloped or ragged leaf edges, often on young trees · likelihood ~5%
Most likely
Caterpillars: cup moth, processionaryBest match
The poinciana looper, a long, thin green caterpillar · likelihood ~5%
Most likely
Psyllids and lerpsBest match
An outbreak of the Moreton Bay fig psyllid · likelihood ~15%
Most likely
Caterpillars: cup moth, processionaryBest match
Processionary caterpillars of the bag-shelter moth; the hairs irritate · likelihood ~5%
Most likely
Cankers and diebackBest match
A canker; the branch beyond it often dies · likelihood ~5%
Most likely
Wood decay fungiBest match
Fruiting bodies of a decay fungus inside the wood · likelihood 20%+ of risk jobs
Most likely
TermitesBest match
Mud tubes, a nest, or mud packed into wounds · likelihood 15–20%
Most likely
Galls (wasp, psyllid, mite)Best match
Citrus gall wasp, with larvae inside the swelling · likelihood ~5%
Most likely
Slime flux and wetwoodBest match
Bacteria in the wood pushing out slime; usually cosmetic · likelihood ~2%
Most likely
BorersBest match
Beetle or moth larvae tunnelling under the bark of stressed trees · likelihood ~8%
Most likely
BorersBest match
A moth borer feeding under the webbing · likelihood ~8%
Most likely
Mistletoe (a parasitic plant)Best match
A parasitic plant growing from the branches · likelihood ~5%
Most likely
Lichen, moss and algaeBest match
Harmless growth living on the bark; it takes nothing from the tree
Most likely
Wood decay fungiBest match
Root or butt decay, which can make a tree unstable · likelihood 20%+ of risk jobs
Brown root rot
If a brown crust also coats the base · likelihood 3–5%
Most likely
Brown root rotBest match
A gritty brown stocking with a white edge; serious · likelihood 3–5%
Most likely
Phytophthora root rotBest match
Collar rot, most often on wet or poorly drained sites · likelihood ~8%
Cankers and dieback
A canker low on the trunk · likelihood ~5%
Most likely
BorersBest match
Frass pushed out by larvae tunnelling in the trunk · likelihood ~8%
Most likely
Armillaria root rotBest match
Fan-shaped fungus with a strong mushroom smell · likelihood 1–2%
Most likely
TermitesBest match
Termites entering from the soil · likelihood 15–20%
Most likely
Phytophthora root rotBest match
Root loss starves the crown · likelihood ~8%
Cankers and dieback
Branches die beyond each canker · likelihood ~5%
Most likely
Phytophthora root rotBest match
Decaying feeder roots, with nothing visible above ground · likelihood ~8%
Brown root rot
Check the base for a brown crust · likelihood 3–5%
Most likely
Sooty mouldBest match
Mould across the canopy, from insects feeding above · likelihood ~15%
Still not sure? An arborist can confirm it on site.
Book a checkWhen tree pests and diseases strike in South East Queensland
The months each problem is most active in South East Queensland. This month is highlighted, so you can see what to look for now.
| Pest or disease | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Anthracnose | ||||||||||||
| Armillaria root rot | ||||||||||||
| Bronze orange bug | ||||||||||||
| Brown root rot | ||||||||||||
| Caterpillars | ||||||||||||
| Decay fungi | ||||||||||||
| Frangipani rust | ||||||||||||
| Galls | ||||||||||||
| Leaf beetles | ||||||||||||
| Mealybugs | ||||||||||||
| Myrtle rust | ||||||||||||
| Phytophthora root rot | ||||||||||||
| Powdery mildew | ||||||||||||
| Psyllids and lerps | ||||||||||||
| Scale insects | ||||||||||||
| Sooty mould | ||||||||||||
| Termites in trees | ||||||||||||
| Tree borers | ||||||||||||
| Tree cankers | Any month, after drought or heat stress | |||||||||||
| Winter bronzing bug | ||||||||||||
- Peak
- Active
- Active all year, inside the tree
Timing from each guide's "when is it most active" section; scale insect hatches from Business Queensland. Weather shifts these by weeks either way.
Common tree pests in South East Queensland
The insects and other pests we find most often on tree health and risk jobs, and the trees they usually attack.
| Pest | Main hosts in SEQ | Likelihood | Guide |
|---|---|---|---|
| Termites (Coptotermes acinaciformis) | Mature eucalypts and other large hardwoods | 15–20% | Read → |
| Scale insects | Lilly pilly, umbrella tree, eucalypts, citrus, mango | ~15% | Read → |
| Psyllids and lerps | Eucalypts; lilly pilly; Moreton Bay fig | ~15% | Read → |
| Borers | Stressed eucalypts, wattles, fruit trees | ~8% | Read → |
| Leaf beetles, incl. Christmas beetles | Eucalypts, especially young trees | ~5% | Read → |
| Fig leaf beetle | Figs | ~5% | Read → |
| Mistletoe (a parasitic plant) | Eucalypts, wattles, sheoaks | ~5% | Read → |
| Galls (wasp, psyllid, mite) | Eucalypts, citrus, figs | ~5% | Read → |
| Caterpillars: cup moth, processionary | Eucalypts, wattles, white cedar, poinciana | ~5% | Read → |
| Mealybugs | Citrus, ornamentals | ~5% | Read → |
| Bronze orange bug | Citrus | ~3% | Read → |
| Possum damage | Eucalypts, fruit trees, new growth | <1% | Read → |
| Winter bronzing bug | Spotted gum, tallowwood, forest red gum | <1% | Read → |
| Polyphagous shot-hole borer | Not found in Queensland; biosecurity watch only | <1% | Read → |
Common tree diseases in South East Queensland
The fungi and diseases we find most often, from decay in old trees to leaf diseases on garden favourites.
| Disease | Main hosts | Likelihood | Guide |
|---|---|---|---|
| Wood decay fungi (Ganoderma, Laetiporus, Inonotus and others) | Large, old or wounded trees | 20%+ of risk jobs | Read → |
| Sooty mould | Any tree with honeydew insects | ~15% | Read → |
| Myrtle rust | Lilly pilly and other Myrtaceae natives | ~8% | Read → |
| Phytophthora root rot | Proteaceae, avocado, wet sites | ~8% | Read → |
| Cankers and dieback (Botryosphaeria and others) | Stressed trees, eucalypts, mango, citrus | ~5% | Read → |
| Powdery mildew | Crepe myrtle, mango | ~5% | Read → |
| Frangipani rust | Frangipani | ~5% | Read → |
| Brown root rot (Pyrrhoderma noxium) | Figs, poinciana, jacaranda, many hosts | 3–5% | Read → |
| Anthracnose | Mango, avocado | ~3% | Read → |
| Slime flux and wetwood | Various | ~2% | Read → |
| Armillaria root rot | Uncommon in SEQ; mainly a southern problem | 1–2% | Read → |
Likelihood is our best estimate of how often each problem turns up on tree health and risk jobs in South East Queensland, not survey data. One tree often has two or three problems at once, so the figures do not add up to 100%.
How to use the tree disease identifier
The tree disease identifier works best when you start where the problem is most obvious and pick the sign that matches it most closely. Look at the tree from a distance first, then up close at the leaves, the bark and the base of the trunk.
- Check the base as well as the leaves. Fungi, crusts and weeping patches at the base are the signs that matter most for safety.
- Try more than one answer. One tree often has two or three problems, such as scale insects and the sooty mould that follows them.
- Read the guide. Each guide shows how to confirm the problem, and what actually treats it.
The identifier narrows the likely cause; it does not diagnose the tree. For a large tree, one near a house, or any sign at the base or roots, a tree health assessment confirms the cause on site. Every guide is in the Pest & Disease Hub.
Tree problem questions
How do I find out what's wrong with my tree?
Start with where the problem shows, the leaves, the trunk, the base or the whole tree, and what it looks like: a coating, powder, bumps, dead bark, fungi or dieback. The identifier above matches those signs to the most likely pest or disease. Many problems look alike, and one tree often has two or three at once, so for a valuable tree or one near a house, a tree health assessment confirms it on site.
How do I know if my tree is dying?
Warning signs include dieback from the top or branch tips, a thinning or yellowing canopy, fungi at the base or on the trunk, cracked or dead bark, and a tree that has started to lean. One sign on its own is not proof the tree is dying, but several together, or any sign at the base or roots, are worth having checked.
What are the most common tree diseases in Queensland?
In South East Queensland, the problems we find most often are wood decay fungi in large and old trees, sooty mould on trees carrying sap-sucking insects, myrtle rust on lilly pilly and other Myrtaceae, and phytophthora root rot on wet sites. Termites and scale insects are the most common pests. The full lists, with how often each turns up, are in the tables above.
Is the lichen on my tree killing it?
No. Lichen, the grey, green or orange crusty or leafy growth on bark, is not a parasite: it makes its own food and takes nothing from the tree, and moss and algae on bark are harmless in the same way. Extension services note it is more noticeable on stressed or declining trees, because a thinning canopy lets in the light lichen likes, so a tree covered in lichen with a thin crown is worth having checked for the real cause. Do not scrape it off, as that damages the bark.
Can a sick tree be saved?
Often, if the cause is found early. Leaf diseases such as powdery mildew and sooty mould rarely threaten a tree, and many root and canker problems improve once the stress behind them is fixed. Decay at the base, brown root rot and advanced dieback are harder, and the question becomes whether the tree is still safe, which is what a risk assessment answers.
Want a definite answer?
Send a few photos of the tree, the leaves and the base of the trunk. You'll get a straight answer on whether it needs an inspection, and a fixed quote if it does.