Lilly pillies are Australian native evergreen shrubs and trees, mainly from moist and rainforest areas of eastern Australia, that have become popular modern garden plants. They are extremely useful screen, hedge and topiary plants, but are also valued for their white flowers and colourful and edible berries, which are usually bright pink to purple. Thanks to plant breeding and development over the past few decades, lilly pillies are available in a range of sizes, including compact plants for low hedges. However, there are a couple of common lilly pilly pests you might notice if you plant them in your garden.

You'll find three main types of lilly pilly in Sydney gardens. These are Acmena spp., Syzygium spp. and Waterhousia spp. There are many named varieties, some of which promise resistance to pest and disease problems that can generally affect lilly pillies. For other varieties, chemical controls are also an option to reduce pest and disease problems.

 

5 common lilly pilly pests and diseases

Here is a guide to some of the most common problems that can affect lilly pillies and how to deal with them. It's quite simple when you know how!

Lilly pilly pests: Psyllid

Psyllid, also known as lilly pilly pimple, is caused by a small insect and affects leaves and new growth. It can be highly disfiguring. While the adults and nymphs are often unseen, the damage is obvious on new foliage, because the adult lays its eggs in emerging growth. As the developing psyllids feed on the underside of the leaves, galls begin to form. These galls appear as tiny craters under the leaves with dimples (pimples) on the topside of the affected leaf. The galls can cause leaves to distort.

A simple way to control psyllid is to prune off affected growth (put it in a bag and into the rubbish bin). It is also possible to spray new growth with a registered pesticide. There are also varieties that are not as susceptible to the psyllid and likely to be free of the problem. Look for cultivars of Acmena smithii, Syzygium australe ‘Resilience’ and Syzygium luehmanii.

A green lilly pilly leaf which is covered in light green discolouration and pimple-like raised bumps. This is caused by psyllid, one of the most common lilly pilly pests.

A lilly pilly infested with psyllid.

 

Lilly pilly pests: Scale

Scales are small, waxy-looking lumps of black, brown or white that appear on stems, twigs and leaves. They can be a pest problem on lilly pillies alongside many other plants. The damaging insect hides underneath its protective waxy cover. Scale can appear on plants that are growing under stress, and may indicate that the lilly pilly is too dry. Prune away badly affected growth and treat the plant with eco-oil, which breaks down the scale’s waxy cover and kills the insect. Improve growing conditions – for example, with increased watering - to stop the scale returning.

Scale can affect many different plants and appear in many different forms. Here, black scale has infested a plant. Scale may also appear white or brown.

 

Lilly pilly pests: Lilly pilly beetle

Lilly pilly beetle is a naturally occurring beetle that feeds on lilly pilly leaves. With the increased cultivation of lilly pillies, the beetle has spread from its native habitat into gardens from south-east Queensland to southern Australia. Its extended range means it is now considered a pest. It is a small, bright green beetle that causes ragged damage to lilly pilly foliage, particularly Syzygium varieties. Both the adult and larvae feed on leaves. Remove beetles by hand or treat with a product registered for leaf-eating beetles.

 

Lilly pilly diseases: Sooty mould

Sooty mould may be found on leaves as a black coating. It is caused by a mould that grows on the exudate of other insects such as aphids or scale (above). While sooty mould can be removed with eco-oil or a soap spray, it is also important to treat the insect feeding on the plant to stop sooty mould returning.

Sooty mould is a common occurrence on lilly pillies.

 

Lilly pilly diseases: Myrtle rust

Myrtle rust is an introduced disease that affects many members of the myrtle family including lilly pillies. It attacks leaves and twigs and has a distinctive yellow rusty appearance. It spreads easily and causes leaf discoloration, distortion and die back. Carefully prune off affected growth (immediately bag, seal and bin or burn) then spray the plant with fungicide. The disease can be controlled with regular applications of copper or another registered fungicide. Susceptibility to the disease seems to vary within lilly pillies. Resistant varieties include ‘Sublime’ and ‘Sweeper’.