More than 700 types of eucalyptus exist. In California, the eucalyptus has gained popularity in landscape design, and it is used as a shade tree, a screen and as a wind break. It is one of the tallest trees in the world, and it has existed in Australia for millions of years. The eucalyptus tree is able to withstand extreme conditions, such as poor soil, drought and fire. Recently several diseases that affect the eucalyptus in Australia have found their way to California.
A variety of pests infest the eucalyptus tree--the eucalyptus longhorn borer, eucalyptus gall wasp, leaf-eating beetles and psyllids. Not all species are attacked by the same insect, and some species are not attacked by any of these pests.
The invading pests have found their way to California, but what is of concern is that their natural predators are not present in California, making a natural solution impossible. These pests are increasing at a rapid rate. Scientists are conducting research on various predators and are looking for ways to introduce them into the habitat. Birds and dragonflies may provide some control by reducing the number of psyllids.
There are no known chemical treatments. Even if there were chemical treatments, they would not be practical due to the size of the trees. Scientists are working to develop systemic insecticides. Since systemic insecticides are delivered through the tree's root system, the height of the tree would not present a problem when it comes to applying the insecticide.
Know the species of your eucalyptus tree. Once you know the species, you can identify the pests likely to attack your tree. And once you know the pests that may attack your tree, you will know what the signs of infestation are. For instance, if you notice that the new growth on your tree is being attacked, it is more than likely the redgum lerp psyllid.
The best defense against these pests is to keep the eucalyptus tree healthy. Pests usually attack stressed or weakened trees. When purchasing a eucalyptus tree, look for a species that is known to be disease resistant. In hot summer months, make sure your tree receives deep-root watering, and be careful not to damage the roots of the tree.