Bonsai Pest and Disease Control
Pests We See In AutumnThere are still a lot of bugs around at present such as thrip, caterpillars, spider mite and for those who have Lilly Pillys then we have the dreaded psyllids.
Thrip is a very small whitish coloured insect that attacks mainly Benjamina figs. It pulls the leaves over itself to shelter from other insect predators, which is very effective for them because it means that any contact sprays are ineffective.
It is easy to identify if your fig has been invaded by thrip because the leaves appear to be curled up and they have little pin prick sized black spots all over them. If you only have one or two figs affected then I recommend you remove the curled leaves by hand, wrap them in paper and put them in the bin. Don’t remove the leaves and throw them on the ground because the little thrip will simply high tail it back to your figs!
If you have too many damaged leaves to remove manually, a good spray with Folimat should do the trick. Folimat is a product put out by Yates and is sold in a pressure can or pump bottle and is ready for instant use.
There are several products that will kill thrip, the important thing is that the spray used must be systemic, so it penetrates right to the sap flow and gets into the leaves, where the thrip eats them and dies. If you use a contact spray, most of the thrip will be protected by the curled over leaf and will live to eat another day!!!
Caterpillars are another insect that can be effectively eradicated by hand. Simply pluck them off, with tweezers if you are not sure which ones you could be allergic to and dare I say it….squash them!
If that sounds too blood-thirsty then I suggest you mix up a batch of Carbaryl and spray them, it is very effective as are most contact sprays.
I have noticed in the nursery that caterpillars have totally defoliated one or two of our figs. I wouldn’t mind them helping with defoliation except that they prefer to eat the tender young leaves instead of the old damaged ones.
Spider mite continues to be around in plague proportion. They thrive on the heat. They don’t like things too wet so if you can spare the water make sure you hose the foliage as well as the roots of the bonsai and it may help prevent an attack. Attacks are more likely on unhealthy trees than on the healthy ones.
We see more problems when trees are kept inside or in heavy shade for long periods. The bonsai becomes very weak and when their Carer finally realizes they should be outside and moves them, they are too weak to resist any insect attacks.
Another problem is that the mite become rapidly immune to sprays so try alternating the insecticides you use. You will not be able to see spider mite with the naked eye so it can be hard for the novice to identify. The easiest way is if you see patches of foliage on a bonsai losing its’ colour and turning brown then it is probably spider mite.
Sometimes with a bad infestation you will see signs of webs but not always. Take note though, that not all webs on bonsai are from spider mite. Some are just little garden spiders setting up house in your bonsai, and they won’t do any harm.
Spray spider mite with Natrasoap three times at around 4 day intervals. It will be hard to know if you have killed them at first because the foliage continues to brown from the sap the mites sucked out of them for a few days after the mite has been killed. They are very hard to kill though, so I suggest you stay vigilant. They attack azaleas, pines and Junipers but mostly the trees that we are seeing bought in by customers are Junipers.
Psyllids: A bug that creates major damage to lilly-pilly is psyllids. They are tiny little bugs about the size of a pin head. They embed themselves in the underside of the leaves and suck the sap from the tree. Their presence is easily identified as they leave ‘pimples’ on the top side of the leaves. If you check on the underside of the leaf, up inside the ‘pimple’ will be a little bug.
If it is possible to remove the damaged leaves by hand then do so, but usually they are too numerous and a spray is required. Once again Folimat is recommended as it is a systemic spray and gets into the sap and poisons the psyllid when it sucks the sap.