Why are my Eucalyptus Leaves Turning Brown? Common Melbourne Tree Diseases

Eucalyptus trees are ordinarily very sturdy and generally resistant to diseases. However, as with any plant, things can go wrong.

The challenge is to recognise the problem early and then to take the right corrective action. This can be the difference between losing your eucalyptus and seeing it grow strong and healthy.

What can go Wrong With a Eucalyptus

Eucalyptus can be affected by a number of fungal diseases:

• Anthracnose affects mainly branches, twigs and leaves, causing small brown lesions and growth that is curled and distorted. It is often caused by excessive moisture, especially after spring rain.
• Phytophthora can affect all parts of a tree and causes rot that is apparent from stunted growth, canker on the trunk and stems, and foliage that is yellow and wilted.
• Heart rot causes decay in the limbs and trunk and is more likely to be present in old and weak trees.
• Powdery mildew causes a white growth on leaves and stems, with new growth more susceptible.

Eucalyptus can also be badly hit by variable winter weather, which can cause new leaves to become brown and crispy. The trees never go fully dormant but the sap, which is watery during the growing season, thickens as temperatures drop in autumn while growth slows and woody material forms. If the winter temperature rises for extended periods, however, the sap thins and growth restarts.

New growth can be very susceptible to frost damage, and this is more likely if growth starts too early. New leaves become scorched and brown and branches are also affected. Although a eucalyptus will retain its leaves in most conditions, it will lose them when put under stress and may find it difficult to recover.

Action to Take to Avoid and Rectify Problems

Eucalyptus is very resilient and will often recover from problems. Nevertheless, there are actions you can take to help them.

Diseases are usually caused by wet weather, poor drainage and damp conditions, especially if air does not circulate freely through the centre of the tree. Improving soil conditions and planting in a sheltered spot will help while applying fungicide can cure some fungal diseases. Irrigating in the morning is best since it gives leaves time to dry and some varieties are particularly resistant to disease.

Proper pruning is the action that will best improve a tree’s health and make it more resistant to problems. It should be undertaken in early spring, before new growth starts, and the aim is to remove all the dead wood and open up the tree for proper air circulation.

Always make sure equipment is properly sterilised, that diseased material is disposed of properly and apply wound paint after large cuts to prevent infection.

If pruning is a big job that you think you cannot tackle effectively, get in touch and we will do it properly. Care of all your trees and shrubs is essential to ensure their continued good health and at A.P. Tree Management, we can look after them all to avoid problems in the future.