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Blue oat mites

Blue oat mite populations appear to be enjoying this season's cold temperatures- croppers and pastoralists are urged to be watchful

Blue oat mite adult with its distinctive red splash (Source: cesar)

 

Where have they been reported?

Building on earlier reports in previous PestFacts newsletters, reports of blue oat mites (Penthaleus spp.) and the damage they inflict has continued to escalate in many crops and pastures across northern Victoria and southern NSW (see map). In Victoria’s Northern Country, blue oat mite numbers have been particularly prevalent in cereal crops (particularly barley) that had no seed treatment and in crops coming out of pasture/fallow. In Victoria’s Mallee region, blue oat mites are also being seen in moderate numbers across a range of crops. 

Distribution of blue oat mite reports since mid-May 2015; reports are symbolised by orange squares (Source: PestFacts Map)

 

About blue oat mites

There are three species of blue oat mites, and these attack emerging pastures, canola and cereal crops. In contrast to the redlegged earth mite, they tend to be solitary feeders rather than feeding in aggregations. Their feeding causes silvering or white discoloration of leaves; in severe infestations, blue oat mites can cause distortion or collapse of seedlings.

For comprehensive information on blue oat mites, including their occurrence, lifecycle and management strategies, go to blue oat mite within the new PestNote series.

For assistance with mite identification download the GRDC Back Pocket Guide - Crop Mites. For images of blue oat mites, click here.

Our advice

Remain vigilant for the potential build up of blue oat mite populations as they appear to be favoured by this season, possibly the cold winter. In Victoria and southern NSW, the last 8 weeks has been about 1-2°C cooler than average.

If a spray is required the first step is to distinguish blue oat mites from other mite species, such as redlegged earth mites and Bryobia mites, as this will influence the approach to control. Importantly, one of the three blue oat mite species, Penthaleus falcatus, is more tolerant to omethoate and alpha-cypermethrin than redlegged earth mite.

 

Sources of field reports of blue oat mites

Matthew Bissett – Consultant, AGRIvision Consultants (Victorian Mallee)

Chris Dunn – Agronomist, Landmark (Victoria’s Northern Country)

Simon Mock – Consultant (Victorian Wimmera)

Craig Muir – Agronomist, AGRIvision Consultants (Victoria’s Northern Country)

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