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Soft brown scale

  • Various sized scale
    Soft brown scales (Coccidae) on the back of a leaf.
Scientific name

Coccidae

Description of adult

The species that occurs on lychees and longans has a raised oval brown covering 3-5 mm in length. The surface has a hatched appearance. They are frequently grouped near the tips of young shoots, fruit stalks and on the fruit.

Life history

The species found on lychees and longans is undescribed and many details of its biology are unknown.

Distribution

Tropical and subtropical regions of Australia.

Host range

Coccids (soft brown scales) attack many tropical and subtropical fruits. Host range of the coccid species found on lychee and longan is not known.

Damage

This scale is a minor but frequent pest problem found in both tropical and subtropical regions of Australia.

Adults and nymphs suck the sap of shoots, leaves, fruit stalks and fruit. Protein is extracted from the sap, while the excess containing sugars is excreted over the plant. The sugary excretions provide a medium for the growth of black sooty moulds. The moulds greatly reduce the amount of light reaching the leaves for photosynthesis. Sooty mould is not parasitic.

Control options

Examine five leaves/stems/fruit on 20 trees widely spaced throughout the crop. Spray if more than five out of 100 of these plant parts are infested with five or more scales. Treat ants at the tree base if they are active. Check for scales and sooty mould on leaves, stems and fruit, especially when conditions are humid. If infestation is noted in spring, spray to reduce the population before crawlers hatch and move to fruit clusters. Infestation of panicles spoils fruit and is difficult to control.

Biological

The mealybug ladybird, Cryptolaemus montrouzieri, kills a major proportion of green shield scales but does not attack soft brown scales. Ants milk, protect and move the scales to new localities and keep predators and parasites away.

Chemical

Spray the foliage with recommended chemicals to control the scales. Treat the lower trunk and the soil around it out to 300 mm away to prevent ants from gaining access to the tree. Because they are sedentary, complete coverage is required for good control of scales. A spray droplet must contact each scale to kill it.

Chemical registrations and permits

Check the Australian Pesticides & Veterinary Medicines Authority chemical database and permit database for chemicals registered or approved under permit to treat this pest on the target crop in your State/location. Always read the label. Always observe withholding periods.