Skip to content 
Common Tree Pests and Diseases on the Gold Coast: Spotting Them Early Saves the Tree
The Gold Coast’s subtropical climate, with its warm temperatures, high humidity, and periodic heavy rainfall, creates ideal conditions for a range of tree pests and diseases. Some of these conditions can be managed effectively if identified early; others can destroy a tree within a season or two of becoming established. At NexGen Tree Services, our AQF Level 5 qualified arborists are trained in the diagnosis of tree health issues, and we regularly identify conditions that homeowners and property managers had not noticed or had attributed to drought stress, poor soil, or simple decline. Early identification is consistently the factor that determines whether a tree can be saved.
Myrtle Rust: A Critical Threat to Native Queensland Species
Myrtle rust is a fungal disease caused by Austropuccinia psidii, and it represents one of the most serious biosecurity threats to native Queensland tree species. The disease affects plants in the Myrtaceae family, which includes a very large number of native Queensland species including eucalypts, paperbarks, lilly pillies, bottlebrush, and tea trees. On the Gold Coast, myrtle rust has been present since 2010 and continues to spread through the region.
The symptoms of myrtle rust are distinctive: bright yellow or orange powdery pustules appear on new leaves, stems, and fruit, which then turn grey-brown as the spores mature. Severely affected new growth becomes distorted and dies. In species with low resistance, myrtle rust can kill young plants quickly and progressively damage mature trees by affecting the new growth they produce each season. If you observe the characteristic yellow-orange powdery pustules on a tree in your garden – particularly on a native species – contact a qualified arborist promptly and avoid working with the affected plant in ways that could spread spores.
Ganoderma Bracket Fungi: Root and Butt Rot
Ganoderma is a genus of shelf-forming bracket fungi that cause a progressive decay of the roots and lower trunk of a wide range of tree species. The visible fruiting bodies – hard, shiny, varnished-looking shelf structures that emerge from the base of the trunk or from exposed roots – are the reproductive structures of a fungal colony that is actively decaying the woody tissue within the tree. By the time fruiting bodies are visible, the decay has typically been progressing for years.
Ganoderma decay significantly compromises the structural integrity of the affected tree by replacing sound wood with soft, crumbly, decayed material. A tree with extensive Ganoderma decay at its base may retain most of its crown and appear outwardly healthy while having lost much of the structural integrity that keeps it standing. Trees affected by Ganoderma near structures, over vehicles, or in areas of pedestrian use require urgent assessment by a qualified arborist, as the risk of catastrophic failure under wind loading is substantially elevated.
Phytophthora Root Rot
Phytophthora species are water moulds that cause root rot in a wide range of trees and shrubs. They thrive in poorly drained soils and are common in Gold Coast gardens where irrigation, heavy clay soils, or low-lying positions create conditions of persistent soil moisture. Symptoms of Phytophthora root rot include progressive yellowing and wilting of leaves, dieback from the tips of branches inward, abnormally small leaf size, and decline in tree vigour despite apparently adequate water and nutrients.
Phytophthora is difficult to diagnose without soil sampling and laboratory testing, because the symptoms it produces are similar to those of nutrient deficiency, drought stress, and other root zone problems. Treatment is most effective when the disease is identified early, before extensive root death has occurred. Improving soil drainage, applying registered phosphonate fungicides, and avoiding practices that promote soil compaction and waterlogging around affected trees are the primary management approaches.
Longicorn Borers
Longicorn beetles in their larval stage bore through the wood of living trees, creating tunnels in the sapwood and heartwood that can significantly damage the tree’s vascular system and structural integrity. Signs of borer activity include small round or oval entry holes in the bark, sawdust-like frass (a mixture of fine wood particles and droppings) around entry holes, and in more advanced infestations, dieback of branches and discolouration of bark over affected areas.
Longicorn borer infestations typically occur in trees that are already under some form of stress – drought, disease, poor soil conditions, or mechanical damage. A healthy, vigorously growing tree is generally more resistant to establishment of a borer population than a stressed or declining tree. Treatment of advanced infestations is difficult once borers are established within the wood, which makes maintaining tree vigour and addressing stress factors promptly the most effective long-term management approach.
Scale Insects and Sooty Mould
Scale insects are small, often inconspicuous insects that attach themselves to the bark, stems, and leaves of trees and feed on the plant’s sap. Heavy scale infestations weaken the tree and produce honeydew – a sticky substance that falls on leaves and surfaces below the tree and promotes the growth of sooty mould fungus. Sooty mould appears as a dark, powdery coating on leaves and bark that can significantly reduce the photosynthetic capacity of heavily coated leaves.
Scale infestations can be treated with horticultural oil sprays applied at the appropriate time of the scale’s life cycle. Encouraging the natural predators of scale – including ladybirds and parasitic wasps – by avoiding broad-spectrum insecticide use around the garden supports biological control of scale populations over the longer term.
Contact NexGen Tree Services for a Tree Health Assessment
If you have noticed signs of any of the conditions described in this article on trees on your Gold Coast property, or if you have trees that appear to be in decline without an obvious cause, a professional tree health assessment by an AQF Level 5 qualified arborist is the most effective next step.
Contact NexGen Tree Services on 1300 675 895 to arrange a site assessment. Early intervention is consistently the factor that makes the difference between a tree that recovers and one that cannot be saved.
