I really like how shady our yard is, but I'm not so excited about cleaning up everything that drops off the trees. I can't pick the fruit from the very top of the trees, so it rots and falls to the ground, and then it attracts mice and birds unless I clean it up straight away. I'm getting the trees all lopped back so I can get a break from all the cleaning up all this fallen fruit. This blog is all about how to get your backyard fruit trees lopped so that you don't have to clean up as much fallen fruit.
It's often easy to spot damage to trees that may render them unsafe; the structural damage caused by lightning, gale force winds and vehicle collisions is hardly subtle. However, spotting the insidious internal damage caused by insect infestations is more difficult. This internal damage can be just as dangerous, weakening the tree's structural integrity and causing branches to fall, and sometimes even killing the whole tree.
Recognising the signs of insect infestation and having it professionally removed early is key, so here are two common insects in Australia that can cause serious damage to your trees, along with methods of spotting them.
Giant Pine Scale (Marchalina hellenica)
These scale insects, recognisable by their pillbug-like segmented bodies and bright yellow colour, aren't exactly giants, growing to about a centimetre long. However, their small size does not limit the amount of damage they can do. This invasive species poses a significant threat to many evergreen trees including pine, spruce and Douglas fir, and is quickly becoming the bane of plantations and ornamental gardens alike.
The giant pine scale attacks a tree by boring through the bark to release the tree's sweet sap, which the scale consumes. A large infestation can seriously deprive a tree of nutrients and hydration, and the bore holes left behind leave the tree vulnerable to bacterial and fungal infection, potentially killing the tree and leaving it dead while still standing, a very dangerous prospect in high winds. Infestation in branches can also cause them to drop without warning.
Although the insects are brightly coloured, they tend to hide underneath flakes of bark and in deep cracks, making them difficult to spot. You can generally spot a giant pine scale infestation by the waxy white excretions the insects leave behind, often resembling cotton buds at first glance. An aborist can used insecticidal injections to remove an infestation if it is caught early enough, but advanced infestations may necessitate removing and burning the tree.
Red Gum Lerp Psyllid (Glycaspis brimblecombei)
Thee dainty and rather beautiful insects, native to Australia, attack all varieties of eucalyptus tree and not just the red gum. This makes them a particular pest in urban areas, where eucalyptus trees are favoured by local councils as hardy ornamental trees. The insects themselves are small and iridescent, with green bodies and transparent wings, but seeing the actual insects is rare—instead, you can spot an infestation by the white cones of hard, sticky excrement they hide under. These are usually found attached to the undersides of the leaves.
These insects damage trees in much the same way as giant pine scales do, by boring through the bark and sucking up the tree sap within the wood. In the eucalyptus family of trees, the first sign of this is sudden, unseasonable leaf drop, which can progress to falling branches and, eventually, tree death. Eucalyptus sap tends to flow easily, so you will often see sticky streams of dried sap running down the trunk of the tree accompanied by streaks of black, sooty mould feeding on the leaking sap.
Removing a lerp psyllid infestation is, on paper, relatively easy. Since the insects are attached to the leaves they can be blasted off and killed with a high pressure hose, although conventional insecticides and horticultural oils also work well. The problem is coping with the scale of an infestation, as eucalyptus trees grow to enormous sizes and can bear millions of psyllids. As such, professional help from companies like ARBOR CENTRE PTY LTD is usually required for all but the smallest trees.