Melbourne’s urban landscape is enriched by its diverse tree population, offering canopy shade and environmental benefits. However, tree diseases can threaten this green canopy, compromising tree health and safety.
Whether you’re a property owner, developer, or simply a nature enthusiast, understanding common tree diseases is crucial for effective tree disease management. In this guide, we’ll explore the four tree diseases in Melbourne, their symptoms, causes, and tree disease management strategies.
Early detection and proactive management are key to combating tree diseases in Melbourne. Regular inspections, proper tree care, and consulting certified arborists can help maintain the health and longevity of your trees.
If you suspect a disease is affecting your trees, don’t hesitate to seek professional advice. Healthy trees contribute to a vibrant and sustainable urban environment—let’s work together to protect Melbourne’s green canopy. For expert assistance, contact your Melbourne tree health expert or tree care service today.
Armillaria Root Rot (Honey Fungus)
Symptoms: Trees affected by Armillaria Root Rot often display yellowing leaves, dieback of branches, and white fungal growth under the bark.
Causes: This fungal disease thrives in stressed trees, particularly those in poorly drained soils or with root damage. It spreads through root-to-root contact or infected soil.
Management:
- Remove infected roots and stumps to prevent further spread
- Improve soil drainage and aeration
- Strengthen tree health through proper watering, mulching, and fertilisation
Elm Leaf Beetle
Symptoms: Leaf skeletonising caused by larvae, holes in foliage caused by elm leaf beetles, general decline in health and vigour of tree.
Causes: If you have damage to the leaves of an Elm tree in south eastern Australia, particularly Melbourne or Victoria, it is most likely to be Elm Leaf Beetle Damage.
Management:
- Stem or soil injections of Imidacloprid to be done every three years
- Soil injections should be done as the tree comes into leaf
- Stem injections can be done any time the tree is in leaf
Phytophthora Dieback
Symptoms: Trees suffering from Phytophthora Dieback show wilting leaves, browning roots, poor growth, and eventual death if untreated.
Causes: This disease is caused by a soil-borne pathogen Phytophthora cinnamomi that thrives in poorly drained or compacted soils, particularly in wet conditions.
Management:
- Ensure footwear, tools, and vehicles are clean when arriving and departing an area
- Source pathogen-free plant stock and material
- Dispose of garden waste carefully
- Avoid moving infected soil around the garden
- Improve drainage and aeration
Cypress Canker
Symptoms: Sunken cankers and ringbarking which interferes with the vascular symptoms of the tree, reddish cankers form at the infection site and resin often exudes from around the edges of the cankers or through cracks in the bark, yellowing and dieback of the branches
Causes: Previously this disease was thought to be caused by a single Seiridium species, but scientists now believe that three 3 species (S.cardinale, S.cupressi and S.unicorne) can cause the same symptoms. These fungi have been present in Victoria for more than 50 years.
Management:
- Avoid planting susceptible species on disease-prone sites, such as those with high levels of nitrogen.
- Keep trees healthy to improve their natural defences against an initial infection. If fertilisers are required, they should be evenly distributed around the drip line of the trees. Watering may be needed during dry spells.
- Reduce the chances of branch or stem wounding (for example, by fencing off trees from livestock).
- Prune infected branches a minimum of 10 centimetres below the canker to help prevent infection spreading to the main stems (but take care not to over-prune). Pruning should preferably be done in winter or following dry weather, when spores are less likely to infect pruning wounds. After pruning, wound dressings may help to prevent spore infection. All pruning tools should be sterilised before and after use with either alcohol or dilute bleach.
- Remove and destroy severely diseased plants by deep burial or burning to help to reduce the risk of neighbouring trees becoming infected.