Green Coffee Scale in coffee
Bruno Pinese,
Harry Fay & Rod Elder, Department of Primary Industries and Fisheries.
Green coffee scale (Coccus viridis) on the back of a leaf. Note the black sooty mould
Description
Adult
The adult female of green coffee scale is oval to elongate in shape, with a flattened profile. It is pale yellow-green in colour, and 3-4 mm long. The roughly U-shaped gut is visible through the partially transparent top of the scale as a line of black spots. At the anterior (head) end, there are distinctive black eye spots. The scales have antennae and well-developed legs and, unlike most scales, can move slowly around the host plant. These features can be used to distinguish the scale from other soft scales such as soft brown scale.
Immature stages
Eggs are not seen as they hatch within the female or immediately after laying. Immature scales are similar to the adult female although smaller.
Life history
The females reproduce without mating. The life cycle takes 6-9 weeks and there may be 3-4 generations per year.
Distribution
Green coffee scale occurs from just south of Brisbane to north of Mareeba.
Host range
Longans, coffee, citrus and a wide range of other hosts including the ornamentals such as gardenia and ixora.
Management
Importance
Major and sporadic; potentially serious in coastal areas and occurrence is increasing in sub coastal areas.
Damage
This insect damages coffee by infesting leaves, twigs and fruit, sucking sap and secreting sugary excreta on which sooty moulds thrive.
Action level
Monitor for green coffee scale together with other soft scales once or twice from mid-October to mid-November. Sample 25 leaves from each of 20 randomly selected trees per 1 to 5 ha block. Apply spray if 10 or more leaves are infested with 1 or more scales. Use oil where Integrated Pest Management (IPM) is practised and direct the spray at young scales during early November.
Control methods
Biological
There are one or two small parasitic wasps, eg. Coccophagus rusti and Encarsia sp. that periodically cause significant mortality of the scale. The Kenyan wasp Diversinervus stramineus has been released on coffee in North Queensland. Its effectiveness is yet to be determined. Ants attend the scale for their honeydew and in so doing disturb potential scale parasitoids. When the ants are controlled, scale numbers drop dramatically.
The mealy bug predator (Cryptolaemus montrouzieri) preys on green coffee scale.
The fungus Verticillium lecanii can cause up to 90% mortality of the scale during wet weather in late summer to autumn, particularly when populations of the scale are large.
Chemical
Good coverage is important when applying oil to control scales as they are sedentary.
Recommended chemical
Petroleum oil (narrow range), methidathion (in non-bearing plants only). Good coverage using high volume sprays is important when applying oil to control scales.
Chlorpyrifos on the soil around the base of the trunk for ants.
Ants are attracted to and feed on the honey-dew produced by the scales. They disrupt natural enemies of the scale and should be controlled by spraying the soil round the trunk with chlorpyrifos or banding with tanglefoot. Some ants are predatory on cicada nymphs and their control may lead to cicada problems.
Note: This information was correct at the time of publication. However, it is the user's responsibility to ensure that registered agricultural chemicals are used in accordance with legal requirements. (See Further information). Always read the label.
Further information
- For further information on coffee production contact the DPI&F Business Information Centre on 13 25 23 - local call 8 am to 6 pm Monday to Friday (non-Queensland residents phone 07 3404 6999). E-mail: callweb@dpi.qld.gov.au.
- The DPI&F book Coffee growing in Australia is available through the DPI&F Shop On-line and at some DPI&F offices throughout Queensland. Contact the DPI&F bookshop on 07 3239 3772.
- Visit the DPI website onwww.dpi.qld.gov.au for other DPI&F notes on coffee.
- Infopest CD-ROM contains current national information on registered agricultural chemicals and is available from Infopest, DPI&F, GPO Box 46, Brisbane Qld 4001 or by email from infopest@dpi.qld.gov.au
References
Broadley, R.H., Smith, D., Owen-Turner, J.C.,Chapman, J.C., Banks, A.G. and Mayers, P. 1987, Protect your citrus, Queensland Department Primary Industries, Information Series QI87012.
Smith, D. 1990, Integrated pest management in Queensland citrus, Australian Citrus News 66(12) 6-12.
Smith, D. Beattie GAC & Broadley, R. (eds.) (1997) 'Citrus pests and their natural enemies'. Queensland Department of Primary Industries, Brisbane.
Smith, D. and Papacek, D.F. 1985, Integrated pest management in Queensland citrus, Queensland Agricultural Journal @b111@b, 249-259.
Swaine, G., Ironside, D.A. and Corcoran, R.J. 1991, Insect pests of fruit and vegetables, 2nd Edition, Queensland Department Primary Industries, Information Series QI91018
Information contained in this publication is provided as general advice only. For application to specific circumstances, professional advice should be sought. The Department of Primary Industries and Fisheries, Queensland has taken all reasonable steps to ensure the information in this publication is accurate at the time of publication. Readers should ensure that they make appropriate inquiries to determine whether new information is available on the particular subject matter.
Last updated 10 November 2005
