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Earth mite hatching

There have been reports of earth mites emerging from oversummering eggs in various regions of Victoria. Consultant, Brooke White (CropFacts), has reported redlegged earth mite (Halotydeus destructor) hatchings in the western part of the Wimmera and Western districts, in Victoria. Researcher, John Roberts (cesar), reports small nymphs of redlegged earth mites and blue oat mites (Penthaleus spp.) in various paddocks between Ballarat, Geelong and Cape Otway in the Western district, Victoria. Redlegged earth mite and blue oat mites have also been observed in some parts of the Northern Country, Victoria.

Earth mites attack pastures and a variety of crops such as cereals, oliseeds, lupins and lucerne.  Some species can also survive on a variety of weeds, particularly broad-leaved weeds. For redlegged earth mites, it takes approximately two weeks of exposure to favourable conditions (<20°C and >10mm rain) for oversummering eggs to hatch. This releases swarms of mites, which can attack delicate crop seedlings and emerging pasture plants.

Examine plants for damage and search for mites on leaves and on the soil surface. There are a variety of chemicals registered for earth mites, which if used within 2-3 weeks of emergence can drastically reduce mite populations. However, if numbers are low enough and favourable growing conditions occur, crops can often out-grow the mite damage without necessitating sprays.

Before deciding on the most appropriate control measure, ensure the correct mite species has been identified. Problems can occur when growers use targeted rates of pesticide to control a particular mite pest and have then found another unexpected mite is present that is not controlled by these sprays. For example, pesticide rates of many products used against redlegged earth mites are not always effective against blue oat mites.

Click here for images of the redlegged earth mite. Click here for images of blue oat mites.

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