Diseases on Eucalyptus Polyanthemos Leaves

Redgum Lerp Psyllid

• The foliage of eucalyptus polyanthemos is susceptible to redgum lerp psyllid (Glycaspis brimblecombei), according to the University of California Extension. The insects are 1/8-inch long and light orange, brown or light green in color with yellow blotches. Psyllids infest the foliage and cause damage by sucking sap or juice with their long mouthparts. As they feed, the insects secrete a sticky substance that leads to the development of mold. Psyllid damage leads to extensive defoliation that substantially weakens the tree. Management includes the introduction of natural predators. These include green lacewings, multicolored Asian lady beetle and pirate bugs. Chemical control includes the use of imidacloprid.

Leaf Spot

• Leaf spot is a fungal disease common to all eucalyptus trees, including eucalyptus polyanthemos. The disease is caused by Phaeophleospora destructans and is characterized by the appearance of light brown, round or irregular spots on the foliage and shoots of the tree. Younger foliage is most susceptible to the disease. If not controlled in time, the disease can lead to defoliation. The fungus grows on the foliage undersides. The disease is among the greatly impacting foliar diseases of eucalyptus trees and is referred to as anamorphic fungi. Control includes the use of recommended fungicides.

Eucalyptus Rust

• Eucalyptus polyanthemos and other species of eucalyptus are prone to eucalyptus rust, a serious fungal disease of many other plant families including eucalyptus. The fungal disease is caused by Puccinia psidii and initially infests new stems, leaves and flowers. The disease starts with the appearance of yellow spots that gradually turn into yellow, spore filled pustules. Over the period of two to three weeks these pustules dry and harden. There often is the appearance of galls on branches and stems. Eucalyptus rust leads to stunted growth, deformed foliage and eventual death of the tree. Control includes the use of fungicides.