The best medicine is prevention. It’s especially true of tree health as there are many problems that trees suffer that can’t be well-treated. Trees in good health can defend themselves against insect infestations and pathogens that otherwise may succeed in killing a tree. Keeping a tree in good vigour is the first step in any Integrated Pest Management (IPM) plan, as well as keeping them looking at their best.
Lack of water is the primary abiotic stressor. It is abiotic stress that generally leads to a tree being weakened so scale, borers, and other pest species can destroy a tree. Too much water is similarly damaging, providing the heightened moisture required by fungal pathogens to thrive. Most established trees that have a protection zone dedicated to provision of resources for the tree do not require irrigation.
Mulch provides many advantages for trees. It gives them a protection zone were a tree can take all the soil’s resources without competition. It substantially reduces evaporation of water and temperature fluctuations. Soil microorganisms and macroorganisms obtain food from the organic matter.
One of the most common injuries to young trees is from whipper snippers and to mature trees is root damage from mowers. An exclusion zone of mulch protects trees from both. There is no more important thing you can do than mulch under the canopies of your trees.
Don’t lop branches or have unqualified tree loppers work on your trees. Lopped branches, those cut along the length of branches, either die or form epicormic complexes. They are those long, spindly branches sometimes called watersprouts. They defeat the purpose of pruning since they quickly replace the length of the branch that was removed and are dangerous with most of the branches failing over time.
Some tree faults form naturally. Formative pruning can remediate problematic branches before they cause trouble. If a tree has matured with natural faults it is sometimes possible to correct them through pruning.
Other faults occur due to insect, fungus, or bacteria. It’s nearly always a result of a tree being stressed which is why we put so much emphasis on looking after trees in the first place.
Insects can usually be controlled with an Integrated Pest Management (IPM) plan. IPM is a recognised method of controlling infestations through:
• Looking after the health of the tree,
• Monitoring insect numbers for damaging levels,
• Controlling insects when necessary, preferably with minimal chemicals, and
• Using means other than chemicals when effective.
Fungus and bacteria can cause rot in trees, often being the final cause of their decline. Fungal infections are many times more common than bacterial. Fungal rot is usually broken down into various symptoms:
• Brown rot,
• White rot,
• Soft rot,
• Pocket rot, and
• Fungal fruiting bodies.
Brown rot is a symptom of fungus that attacks cellulose in wood. Cellulose is an important component in plant cell walls. Phellinus noxius is perhaps the best-known cause of brown rot in Brisbane.
White rot attacks the lignin in wood leaving the timber spongey or stringy. Ammilaria species of fungi are a common cause of root rot in Australian trees.
Soft rot is a controversial term as it’s often confused with brown rot. Bear in mind these symptoms are merely descriptive and can be helpful in identifying the actual species of fungus behind decay. Rot is often described as soft rot if the fungus exudes cellulase to break down the cellulose in the wood, and so gives timber a similar appearance to brown rot.
We’ve been finding more cases of pocket rot in poincianas in Brisbane of late. Pocket rot is a symptom of fungi that travels through tree’s own transport system, the phloem, to eventually attack the whole tree. It’s first identified by splits in the bark and weeping of the tree’s sap.
Fruiting bodies, also called conks or bracket fungi depending on their appearance, are a fruit formed by fungi to disperse spores for reproduction. As such they are often a late indicator of a tree with a serious fungal infection.
Bacterial infections are often associated with a foul odour and moist wood. They are typically indicative of a tree in terminal decline.
Trees can be damaged by poor pruning practices, storm damage, natural faults such as crossing branches and leanness of branches and leans. Again, tree pruning can sometimes help but if you have a damaged tree you should contact a level five arborist for an assessment if there is any risk of tree failure causing harm.
Soil is the tree’s primary area for obtaining water, air, and nutrients. Its health is intrinsically tied to trees’ vitality. Aeration, mulch, and fertiliser are the three most common soil amendments but should only be applied after testing. Brisbane Trees and Gardens consider ourselves tree soil specialists as we test soil for all trees we assess, treat, or prune. We very often find the cause of tree problems in the soil and can successfully fix the underlying issue.