Scale on citrus trees is one of the more common pests that appear now. The gardener may not be aware that the sucking insects have attached themselves to the branches and leaves until they notice a trail of ants on the plant.
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The scales exude a sweet, sticky substance called honeydew that is attractive to ants. The ants assist in spreading the scale over the plants in order for them to produce more honeydew.
Honeydew also leads to the appearance of a sooty mould that is actually a black dusty fungus. The sooty mould will soon appear on leaves and stems.
If allowed to remain on a plant, the sooty mould will stunt the plant growth.
Therefore, removal of the scales is necessary for the control and removal of sooty mould.
Small amounts of scale can be removed by scraping the stem and leaves with a toothbrush. However, larger infestations will require spraying with oil, which will suffocate them.
Make the oil spray by blending two cups of vegetable oil with one cup of pure liquid soap, and mix it until it turns white. Dilute one tablespoon of the emulsion to one litre of water and spray all affected areas thoroughly.
Do this during mild weather, because if it’s hot it may burn the plant’s leaves.
PRUNE TIME
Bush camellias and azaleas can be pruned now, as this treatment can be used to remove older, less productive wood and encourage new growth. This will result in a much better flowering display next season. Camellias and azaleas will survive a hard prune, cutting back into old wood.
While pruning these plants, it is a good opportunity to check for borer damage. Borers come in different forms but their presence is evident through a mass of fine sawdust-type material that can be found near the junction of branches and stems. If this material is scraped away, it will usually be noticed that areas of bark, often in “trails”, have been chewed away.
If there is serious borer infestation, then the trunk or branch may be almost completely ring barked. A hole will be present, going into the plant material. This is where the borer has been working.
Various options are available for treatment, with some gardeners preferring a particular action. Some like to insert a piece of soft wire into the hole to get the borer, which will be in the form of a grub. The hole can be sprayed with a general-purpose insecticide. The use of derris dust, maldison, kerosene or dolomite are also techniques favoured by some gardeners.
A piece of putty or other soft material can be used to plug the hole. In some instances it may be preferable to remove the affected part of the plant completely by sawing or cutting it away from the main plant.
As the plant will have been under some stress because of the borer attack, an application of Seasol will help it regain good root structure and good growth.
Regular inspections of the plant will ensure that treatment can be carried out before the problem becomes too severe.
