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Earth mite

Numbers of earth mites have increased in recent weeks and are now causing damage to crops in some areas. Researcher, Aston Arthur (University of Melbourne), reports observing a marked increase in redlegged earth mite (Halotydeus destructor) numbers in a canola field trial east of Shepparton, in the Northern Country district of Victoria. In plots that have had no insecticide treatments, canola plant numbers are significantly lower than in plots that were sprayed with an insecticide prior to emergence.

Research consultant, Valerie Caron (cesar), reports finding increased numbers of both redlegged earth mites and blue oat mites (Penthaleus spp.) in several field trials around Colac and Winchelsea in the Western district of Victoria. Significant feeding damage was evident on both pastures and canola plants in the trials. Agronomist, James Christie (JSA Independent), has observed significant numbers of blue oat mites in one canola crop, along with low numbers of redlegged earth mites in several pastures around the Donald area, in the Wimmera district of Victoria. Damage is minimal and James says spraying is not warranted at this stage. Many other reports we have received in the last month suggest similar situations elsewhere.

Redlegged earth mites and blue oat mites are both significant pests of pastures and many broadacre crops in southern Australia. In a typical season, both pests are found in high numbers across a wide area of Victoria and New South Wales. This season however, overall mite numbers have generally been lower than normal. It is likely that significant spring and summer rainfall and flooding experienced in many areas has had an adverse effect on the production and survival of over-summering diapause eggs of these mites. For more information on redlegged earth mites and blue oat mites, refer to PestFacts Issue No. 3.

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