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How to treat common tree pests in Melbourne

elm leaf beetle

Howdy Amigos, 

Well, spring has well and truly sprung in our neck of the woods.  Rain, sun, rain, sun rinse and repeat. I don’t know about you but as soon as I finish mowing the lawn it’s ready to be done again.  I kind of feel like homer trying to be clean shaven but has no hope at keeping it at a respectable length.

 

Homer Shaving

 

And, as annoying as the capeweed is it is actually pretty sweet to see how determined those little yellow flowers are to come back even when I unceremoniously chop their heads off.  Reminds me to never give up! 

Crafty Capeweed

So what up this week?

Well, we’ve noticed a few calls coming in recently about pests and critters that folks are concerned about when it comes to their beloved gumtrees.  So this week we’re here to set the record straight about a few of them. 

Some pests are a hazard to your plants and need to be taken care of with the full force of our arsenal.

However,  there are some that with a little bit of knowledge and know how you can get rid of yourself or will find they don’t cause too much of a problem at all.

Gum Tree Scale

Gum tree scale is a common pest that infects the young stems and leaves of a gum tree. 

Recognisable by their white/brown felt like sac with a small opening at the end, they most often clump together on stems and twigs that can be entirely covered in some parts.

The wingless female bug lives in the sac and sucks up the sap from within the tree. After they gorge themselves they excrete a sticky sugary substance known as “honeydew”. Droplets of the honeydew can fall onto other parts of the tree and can leave a sooty mould fungus often infects this secretion and causes the leaves to turn black.

This fungus can interfere with the photosynthesis of the tree and you may find the leave yellowing and dropping off when it has caused enough trouble. 

Small reddish nymphs or “crawlers” will emerge from the sac once the female gives birth and  move out of the sac to find their way to other parts of the same tree or can be blown long distances by the wind to other trees where they will settle down and begin a new cycle

Gum Tree Scale Melbourne

How do you manage Scale?

Scale is generally nothing to worry about and can be managed from home,  the main tip here is to manage infestation before it takes over. There are also a number of natural predators to scale that will likely keep the population under control. laDYBIRBut here are our tips; 

  • Monitor your plants regularly. If you have a plant that is prone to scale, consistent checkups will help to manage and eradicate it early. 
  • If the infestation is limited to one small young branch you can prune that branch. Just make sure you get rid of it and don’t leave it near your other plants. Then just monitor it. 
  • If the scale population is small enough you can scrape them off the plant and squash them (be mindful to always use gloves and some irritation may occur) 
  • You can also suffocate the scale by using an oil based soap wash on the plant. (ned recommendations here or suggest homemade?) 
  • Often gum tree scale will resolve itself due to the cyclical nature of the bug and the presence of natural predators. 

 

Gumleaf skeletioniser

Gum leaf skeletoniser is a common pest in Eucalypt trees and can be found all over Australia. 

Identified as hairy caterpillars with brown and yellow spots and a cap or head dress on top of the head. You may find a hairy mass of the young larvae in a  cluster on the surface of leaves. Thes hairy spike will cause a sting and a lasting itch if you touch them with your hand. 

When fully grown the caterpillars will form a long cocoon that is usually located on the lower parts of a tree, fallen twigs or the forest floor. 

Gum leaf skeletonise

The young larvae of this species take great delight in eating the fleshy parts of the leaf leaving behind a skeletal appearance while the older larvae will eat the entire leaf. 

This makes the damage more unsightly than harmful. However, given a trees reliance on healthy leaf matter to absorb food through the leaves if there is a large or continual infestation it can impact the photosynthetic properties of the tree. 

The most effective way to prevent damage from gum leaf skeletoniser is to monitor the plant and remove any egg batches you find if they are on low level branches. Chemical control is rarely recommended with the exception of large scale plantations. 

This pest isn’t something to be overly concerned about in small amounts. If you find the egg batches you can remove and destroy them and that will contribute to controlling them. Otherwise, there isn’t a great deal to be done about this one.

Elm leaf beetle

This little bugger is like an unwanted Christmas gift. From November and into February Elm leaf beetle infestations can cause some damage to your lovely elm trees. 

This is a critter you need us for. 

Around 6mm long with a green and black stripe along the back these beetles lie dormant in winter. In spring they emerge to wreak havoc on young leaves. 

elm leaf beetle

Laying clumps of yellow coloured eggs on the underside of the leaf in Late November and hatching 7-10 days later, the new larvae feed on the underside of and skeletonise the leaf. As they grow the older larvae move to the top and cause further damage (called ”shotholes”)

This extensive damage can cause discolouration and defoliation. This defoliation could impact the trees ability to photosynthesise. Which as we know is the tees main source of food for growth and energy. 

This is an extensive concern among elm trees as these beetles often move about on cars that park around elm so they hitch a free ride to a new victim with very little trouble. 

Elm leaf beetle damage

Without attention to this problem, continual infestations of the elm leaf beetle could cause a tree to die over the course of a few years. 

Control of the elm leaf beetle isn’t as simple as the others we’ve mentioned above. This fella needs more intense control to keep them at bay and avoid lasting damage to these beautiful trees. 

At tree Amigos we recommend a trunk injection with an insecticide called Silvasheild. This is placed in the cambium layer of the trunk (cambium is th layer just under the bark – add a diagram) 

As the tree absorbs water in an upward fashion it transports the insecticide to the leaves killing the beetles. 

Tree injections are considered a low risk option and the pay off is a great improvement to the aesthetic and health aspect of your tree. 

These three tree pests (try saying that three times) are the most common we encounter. But as you can see only one really needs professional treatment.  A simple and effective treatment at that. 

If you have an elm tree in trouble on your property give us a call or visit the website and we’ll give you all the details to get it sorted ASAP. 

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