Overview of forestry pests and diseases

Trees

The following resources contain information about the pests and diseases that affect the forestry industry:

Stem borers

Stem borers are grubs or caterpillars (moth or beetle larvae) that tunnel through and feed on wood, causing damage to twigs, branches, stems and trunks. Stem borers can reduce wood quality in harvested logs and timber. Stem borers include:

• five-spined bark beetle
• giant wood moth
• longicorn borers
• sirex wood wasp.

Symptoms include:

• the presence of sawdust (frass)
• damaged or lifted bark, and ring-barking (girdling)
• exit holes
• cracking and swelling
• leaking sap
• withered branch tips.

Leaf-chewing

Leaf-chewing beetles and mites feed on tree foliage and can cause extensive damage, especially to young trees. Leaf-chewing insects include:

• christmas beetles
• gumleaf skeletoniser
• leaf beetles
• swarming scarab beetles (spring beetles).

Symptoms include:

• jagged or ripped leaf edges
• reduced leaf area
• distortion and dieback in young leaves
• defoliation.

Sap-sucking

Sap-sucking insects affect trees by removing large quantities of water and nutrients, causing wilted or shrivelled growing tips. Sap-sucking insects include:

• lerps and psyllids.

Symptoms include:

• leaf discolouration and withering
• leaf loss in severe infestations.

Leaf miners and gallers

Leaf miners feed inside the leaf between the top and bottom surfaces. Gall-formers are small wasps or flies that lay eggs between the leaf surfaces where the hatched larvae feed. Leaf mining insects include:

• plate galler
• erinose mite.

Leaf miner symptoms include:

• dried, silvery or brown leaf tissue
• leaves shedding early
• severe infection can cause defoliation.

Gall-former symptoms include:

• the tree developing galls, which are swellings in leaf or shoot tissue that surround the eggs and larvae
• sometimes significant defoliation or tree malformation.

Fungal diseases

Fungal diseases can affect trees by infecting their leaves, stems, bark and roots. Fungal diseases include:

• brown root rot (Phellinus noxius)
• kirramyces leaf diseases
• myrtle rust
• pink disease
• quambalaria shoot blight.

Leaf symptoms include:

• spots, blotches and blisters
• powder
• changes in colour (discolouration)
• defoliation, particularly in the lower crown.

Stem and branch symptoms include:

• dying patches
• bark stains
• cracks and splits (sometimes with leaking sap)
• sheets of fungal mycelium (dense strands of fungal threads) under the bark.

Timber

The Biosecurity Act 2014 outlines control measures relating to exotic timber pests in Queensland.

Termites

• Subterranean and drywood termites
• West Indian drywood termite

Borers

• Cigarette beetle
• Common furniture beetle
• Pine bark anobiid
• Powderpost beetle
• Queensland pine beetle

Also consider...

• Learn more about forestry pests and diseases.
• Read Forest health guide: symptoms of insect and fungal damage on trees—a reference guide to common damage symptoms in trees.
• Read Healthy hardwoods: a field guide to pests, diseases and nutritional disorders in subtropical hardwoods which has a focus on subtropical plantation hardwoods.
• Search the Pests and diseases image library (PaDIL) to help identify exotic and native pest and disease organisms.