Eriophyid Mites Affecting Ornamental Plants

Note Number: AG0180
Published: June 2000
Updated: February 2010

 

Eriophyid mites (Eriophyes spp.) are so small and difficult to see without some magnifying device that they often go undetected. They are wormlike and range in length from 0.1 to 0.3 mm. They also have considerable reduction in body structure; the two pairs of hind legs and most body setae have been lost and the front legs are reduced. The symptoms they produce include odd colour patches on leaf surfaces, leaf margins that roll inward or downward, swollen and distorted leaves, galls, russetting, and "witches brooms". The symptoms are often confused with the symptoms of

growth regulator or herbicide damage.

Camellia rust mite

In Victoria this mite causes brown, roughly circular patches or rings in the dark green of the upper surface of camellia leaves. The symptoms are similar to those caused by some viruses on other plants. The cast skins of the mites can often be seen as minute white specks on the backs of infested leaves. The upper surfaces of heavily infested leaves tend to curl down slightly and in severe infestations the under surface of the leaves turn a rusty brown colour. In warm weather the germination time is about two weeks.
Infestations that cause serious damage are rare in Victoria. The mite populations fluctuate markedly as a result of various environmental factors but if the mites cause appreciable damage spraying with a miticide may be warranted.

Carnation shoot-mite

The eriophyid was found infecting carnations in Australia in the mid-late 1980s. The mites live between the leaf bases and stems and are numerous on the lower portions of the plants. The plants lose colour and may become distorted and stunted, with a greasy appearance.

Other eriophyid mites

Various native eriophyid mites occasionally cause "witches brooms" on eucalypts, leptospermums and other native plants. The leaves are drastically reduced and the shoots are bunched together to make a compact mass. Sometimes the leaf surfaces may show red markings where the mites have been feeding. Control measures are usually not required because often only a small proportion of the plant is affected and environmental factors appear to control the mite populations.

Contact/Services available from DPI

For effective pest and disease control, correct diagnosis is essential.
A commercial diagnostic service is available at DPI Knoxfield. For further information, contact the Diagnostic Service. ph: (03) 9210-9222 or fax (03) 9800 3521

Further information

Contact the Customer Service Centre of the Department of Primary Industries, Victoria at 136 186

For information relating to the safe and appropriate use of chemicals, including management of chemical residues and licensing requirements, call the DPI Customer Service Centre of 138 186 and ask to speak to your local chemical standards officer or visit www.dpi.vic.gov.au/chemicalstandards.

Acknowledgements

This Agnote was developed by David Williams, Bioscience Research, Victoria, June 2000.
It was reviewed by Harold Adem, Farm Services Victoria, February 2010.