How to rescue your citrus trees from pests and disease
As citrus are ripening now and over the next few months, I thought it would be a great idea to talk about a few of the pests associated with these plants, and most importantly, what you can do to protect your citrus from them.
Enemy number one: Scale
Scale are sap sucking insects that are found on the leaves and branches of your citrus trees. If your tree is looking unhealthy, inspect the branches for ants climbing up and down your tree. This can be a sign of scale, as they secrete sugar which attracts the ants.
There are different types of scale, from the hard shelled brown ones to the soft white ones.
Scale insects attach themselves to the leaves or stems of your citrus and start to suck away at your plant. They excrete honeydew that is attractive to ants, which in turn creates sooty mould. When your plant is infested with scale, the leaves usually turn yellow. Also if you have cracks in your bark, scale can live in these, which are quite hard to see. It pays to examine your tree thoroughly.
If scale is left unchecked, your tree could become very weak and unhealthy.
Remedy number one: Fight scale organically
To treat scale, spray with a good oil. I use EnSpray 99, as I have had great success with this. Spray the infected areas and this will suffocate the scale and cause the scale to die. When you touch it, it will fall off the tree or you can rub off with a cloth. Repeat spraying if the infestation is bad. This year, I have found scale on many, many plants – even natives – so it is not really specific to tree varieties.
Enemy number two: Borer
How do you know if your citrus tree has borer?
The tree will lack vigour and have holes along the branches. In some cases, you will even be able to see mounds of sawdust.
Remedy number two: How to remove borer
Borer grubs are dormant for the next couple of months, so it is an ideal time to cut out and remove any borer. This is your time to act! Really, when it is dormant is the only time to cut it out, otherwise the grub will lay egg on new cuts and then they will bore into the new growth of your tree.
It is SO IMPORTANT to remember to either burn or dispose of your infected branches. The totally organic way of dealing with borer is to insert a G string from a guitar down the hole to pierce the grub, however this could take some time (and patience!). At Grow Inspired, we typically use a squirt of CRC down the hole, as this smothers the grub and causes it to die, without harming the trees. Following this, apply pruning paste over the holes or wounds to protect them from further infestation.
Last year, I was lucky (or unlucky) enough to see three borer grubs and I was shocked to see the size of them. Fat and juicy, and half the thickness of my pinky finger!!!
Borer can kill citrus trees if left untreated. Also you can keep your tree alive by removing the dead wood and keeping an eye on your tree, looking for new sawdust trails. Over the past year, I have had a client lose a huge branch from their lemon tree due to borer, where the wood was completely eaten through.
Take action and save your trees.
If you inherit land with an old lemon tree full of borer, you might well be wise to invest in a new one in case the old one is not able to be brought back to life.
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