Tips
Scale season
Scales are sap-sucking insects that come in many shapes and sizes, but they all share one characteristic – the adults build a coating that disguises and protects the pest beneath.
Generally, scales fall into two groups. Soft scales are the most easily seen, as they have a thicker coating that’s clearly obvious. Hard scales are smaller and less noticeable but can often cause more damage to the plant.
Some of the most common soft scales are white wax scale, pink wax scale and soft brown scale. Soft scales are often seen clustering along the mid-rib of the leaf. As well as sucking sap from the plant, most of these soft scales produce honeydew, a sticky substance that spreads out over the leaf. A black fungus called sooty mould (pictured) can grow on this layer. As well as looking ugly, this interferes with the plant’s ability to function.
Soft scales are easiest to control at this time of year because it’s their breeding season. The immobile mother scale lays her eggs under the protection of her scaly covering. After the babies hatch out, they head off to find a part of the plant where they can settle down and begin their sap-sucking life. They’re at their most vulnerable in this mobile stage.
Hard scales, which are flat and more difficult to control, don’t produce honeydew. Some hard scales (such as San Jose scale or rose scale) can cause accompanying dieback or discolouration on leaves or stems. Hard scales breed at any time of year, so it’s more difficult to catch them in their vulnerable juvenile stage.
Controlling scales
- Remember, summer is the best time to treat soft scale. Use Yates Bug Oil or Conqueror Oil because both produce a layer of oil that smothers the scale (especially the young ones). Choose a cool day – never use oil when weather’s hot. Conqueror Oil can be used at a much stronger rate on deciduous plants when they’re in their winter dormancy.
- Confidor is also suitable for controlling soft scales. Spray once, then wait about ten days and give a follow-up spray.
- In the early stages, most scales can be removed by gently scrubbing with a soapy brush.
- Ants love honeydew, so they’ll encourage scales and drive away scale predators. Hence, controlling ants will help to reduce scale numbers. One simple way to do this is to wrap a sticky band around the trunk of scale-infested plants. Do this at the end of the day and the ants won’t be able to climb up and get to the scales next morning.
- Some hard scales can be controlled with a winter application of Yates Lime Sulphur.
- Sooty mould will gradually flake off once the scales have died.
Comments (8)
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Faye
Yates site member
07:34, 12 January 2010
Thank you for this scale article, our tangelo and tamarillo trees have sooty mold at the moment and my husband was'nt sure what to spray with .
Deena
Yates site member
10:11, 12 January 2010
Thanks for this article my lime tree which is in a container has just been attacked the only reason I noticed was because of the ants. Thanks for the tip on controlling them to.
Barbara
Yates site member
10:47, 12 January 2010
Thanks for that..will be off to buy some, as my grab apple tree looks a little sad.
pat
Yates site member
13:11, 12 January 2010
Am a first time gardener. Appreciate all the help I can get
Ann
Yates site member
17:16, 12 January 2010
Our lemon tree is constantly being affected each year inspite of using conquerer oil .Will try again this week if overcast.The tree is over 40 years old and fruits very well but looks unsightly.
Jen
Yates site member
17:34, 12 January 2010
Have just sprayed the very old lisbon lemon tree-thanks for that article on scale insects and ants-it really helps when you can put all the pieces together.
Bev
Yates site member
17:40, 12 January 2010
I have a Clematis that is covered in Scale, and try not to use sprays, but this year it is so bad I will be trying Yates Conqueror Oil
Kerry
Yates site member
15:29, 31 January 2010
I noticed the ants walking up and down the side of my lime tree and upon closer inspection i saw the scale under and on top the leaves i used Yates Conqueror Oil to clean up this problem .
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