- Written by Nadia O’Carroll
Myrtle rust (Uredo rangelii) is a type of fungus; it is a serious pathogen that affects plants in the Myrtaceae family, including iconic Australian native species such as lily pillies, bottlebrush, tea tree and eucalypts. The disease presents a risk of significant damage to the natural environment, Australia has approximately 2,253 native species of plants belonging to the family Myrtaceae (about 10% of Australia’s native flora). This plant family is an important and often dominant section of many Australian ecological communities including eucalypt-dominated forest and woodland, rainforests, shrublands, and heaths.
The disease also has the potential to damage a wide range of commercial plant industries, private gardens and community parks and gardens.
The list of known host plants stands at 36 but it is likely to increase as the fungus spreads.
The fungus was first identified in April 2010 in a flower and foliage producer in NSW; it has now been detected in Brisbane and other areas of South East Qld. The disease has been found in bushland, nurseries, gardens and bush food producers.
The spores of myrtle rust spread easily; they can be carried on the wind or transferred by insects, birds and animals. Human activity can also facilitate the spread through the movement of infected plant materials, contaminated vehicles, contaminated transport and packaging and fungal spores attaching to people’s clothes, shoes, tools and equipment.
Due to myrtle rust’s existing distribution, and the ease and speed of dispersal it has been nationally agreed that it is already impossible to eradicate this disease from Australia. Action by government agencies such as Biosecurity Qld will concentrate on containment by locating, removing and treating infected plants and other control methods deemed appropriate.
The first signs of myrtle rust infection are tiny raised spots or pustules, after a few days these spots become lesions which are filled, usually with bright yellow or orange yellow spores, and occasionally with dark brown spores. The lesions may appear on leaves, shoots, buds, flowers and fruit. As the disease progresses leaves may buckle and twist, new growth dies, defoliation occurs, the growth habit becomes stunted and distorted and finally the plant may die. Scientific studies and observations indicate that plants can vary greatly in their susceptibility or resistance to the disease.
The disease does not appear to be harmful to humans and animals.
If you suspect that you may have infected plants on your property, or you have observed infected plants in a park or bushland do not under any circumstances move or dispose of the plant. Try to avoid contamination and please immediately contact Biosecurity Queensland on 13 25 23 or the Exotic Plant Pest Hotline on 1800 084 881.