Councils maintain tree health to ensure public safety, environmental sustainability, and urban aesthetics. Healthy trees reduce the risk of branches or entire trees falling, which can cause property damage or injuries. Trees also improve air quality, mitigate climate change by absorbing carbon dioxide, and provide habitats for wildlife.
- Tree root management
Tree growth is strongly influenced by below-ground conditions. Tree roots will flourish wherever moisture, oxygen, nutrients, and soil structure are favourable.
Tree root growth in the urban environment is highly modified and is not governed by property boundaries. Root pathways cannot be predicted.
Tree root damage to footpaths, roads and roadside kerbs may happen when space for root growth is limited. Tree root damage to pipes can occur when the pipes are damaged, broken or cracked allowing roots to invade the pipe.
Some of the ways tree root damage can be avoided is by:- constructing root-resistant footpaths and foundations where possible, and
- containing tree roots within a defined area, while still providing for a tree’s growth requirements.
You can ask Council to investigate tree root damage from trees on public land, if you feel they are causing damage to your property, by making an online request.
Trees will not be removed for unsubstantiated claims of damage from tree root activity.
- Tree insect infestation
Seasonal insect infestation is a risk for every Council tree every year. In most cases, infestations are harmless to people and pets and cause little harm to the tree.
Late summer is notorious for early signs of disease and pests, and Council will only address seasonal infestations in the most extreme cases. Tree health is usually unaffected, and the insect population will disappear in the cooler months.
Lerps (Psyllids)
Psyllids are Australian native, sap sucking insects that usually attack the Wallangarra White Gum (Eucalyptus scoparia). They can also infest commonly planted and naturally occurring native tree species, particularly during hot and dry conditions.
The psyllid populations usually explode every four to five years. Generally, a tree will withstand a psyllid infestation though it may decline if it is already under stress.
Control options of psyllids are limited, especially in urban areas.
Psyllids have several natural predators that keep their numbers in check, including spider mites, lady beetles, small bush birds and rosellas.
Psyllid infestations cause:
- trees to temporarily lose their leaves,
- discolouration of leaves – brown/red mottled appearance
- white spots on the leaves (lerps), and
- a non-toxic, sap-like substance called honeydew appears on the leaves.
Psyllids suck sap from the leaves of the trees and form a waxy, sugary layer over themselves called a lerp. This waxy layer protects them from natural predators and the harsh Australian climate. This sap sucking process is responsible for the clear, sticky substance covering and dropping from the leaves. Populations of psyllids eventually collapse; once this happens, natural predators increase and essentially finish them off. Most trees recover reasonably well.
You can find more information at Land for Wildlife.
Credit: Eco organic garden Elm Leaf Beetle (Xanthogaleruca luteola)
The Elm Leaf Beetle is a significant pest affecting elm trees during summer. Severe infestations can cause trees to lose their leaves and seriously weaken and leave them prone to other pests and diseases. If left untreated, these beetles can rapidly defoliate a tree, particularly in warmer weather, and several years of infestation can cause tree death.
During spring, tiny eggs are laid in clumps on the underside of leaves. Beetle larvae are tiny and initially black and can grow to 12mm long. After hatching and feeding on the leaves the larvae travel down the trunk where they pupate in the soil below, emerging as beetles after one to two weeks. Adult beetles appear in spring and are about the size of a large grain of rice and are yellowish-olive green in colour with two black stripes.
Elm Leaf Beetles create a series of small holes in the leaves where the larvae destroy all but the leaf veins, creating a skeleton effect. Trees that are affected can lose their leaves by mid-summer, meaning there is no summer shade or autumn colours, reducing their ability to reserve energy over winter.
Total eradication of the Elm Leaf Beetle is challenging. The primary goal is to maintain beetle numbers (and damage) to an acceptable level. We have a two-year treatment regime for Council managed Elm trees to minimise damage to the tree.
Credit: Arborcraft Plague Soldier Beetle (Chauliognathus lugubris)
With an increase in rainfall and humidity during spring and early summer you are more likely to encounter the native Plague Soldier Beetles. When conditions are ideal these beetles will gather in large numbers to mate and feed on the nectar of both native and fruit trees as well as vegetables and other garden plants.
These beetles are harmless and do not cause a great deal of damage to the plants. Their larvae live on the ground and feed on other insects. To deter predators, beetles can secrete a poisonous chemical. There is not much you can do to control them and in time the beetles will disperse and continue on their way.
Credit: Museums Victoria Spitfires (Sawfly larve)
Spitfires belong to the same insect group as bees, wasps, and ants. The sawfly gets its name from the saw-like ovipositor (a tubular organ) of the female, that she uses to drill holes into eucalyptus leaves to lay her eggs.
Depending on the species, larvae can range in colour from dark blue or black to yellow and brown with a light covering of white, bristly hairs. Adults are mainly black or brown, with yellowish markings. Although they are closely related to wasps, sawflies do not have a narrow waist and stinger.
When threatened and to scare off predators the larvae raise their heads and let out a strong-smelling, yellow-green liquid made up of eucalyptus oil. This is why they are called spitfires.
Resembling hairy caterpillars, the larvae are quite noticeable gathering in large groups on the branches of eucalyptus trees during the day for protection. They spread out to feed on leaves at night. Adult sawflies are harder to see, choosing to remain hidden.
Spitfire larvae feed on the young and new leaf growth of eucalyptus trees and can strip branches of all leaves. Trees will recover when they put on new growth during spring-summer. Tree death is not common but repeated attacks can cause severely deformed growth.
One of the spitfire’s natural enemies are parasitic wasps who lay their eggs either on or in the body of the sawfly larvae. Once the wasp egg hatches the wasp larvae will eat the sawfly larvae alive from the inside. These wasps are biological control agents and keep the population of spitfires under control.
Credit: Project Noah You can Report a tree issue if you are concerned about the health of a street tree and we will conduct an inspection and undertake work if necessary.
Request a Council tree service