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Blue oat mites

Blue oat mites (Penthaleus spp.) are also active in many regions after hatching from over-summering eggs. Agronomist, Rachael Webb (Landmark), has found blue oat mites affecting many early tillering oat crops near Inverell, in the Northern Tablelands district of New South Wales. In some cases more than 10 mites/plant could be found when visually searching, and plants were showing obvious signs of feeding damage. Rachael says many crops are moisture stressed and the mites are further affecting plant development. Where chemical control has been warranted, crops have generally been sprayed with an organophosphate chemical.

Blue oat mites are often mistaken for redlegged earth mites due to their similar appearance and sympatric life-cycle. However, blue oat mites and the redlegged earth mite differ markedly in their biology and tolerance to pesticides, and require separate management strategies. Blue oat mites are the most abundant earth mites in many cropping and pastoral areas of Victoria, Tasmania and New South Wales. Blue oat mites can be distinguished from other mites by their blue-black coloured body and characteristic red mark on their back. Click here for images of blue oat mites.

If chemical control is warranted, blue oat mites should be targeted within 2-3 weeks of emergence. This approach should protect newly germinated seedlings, which are most prone to mite attack. Be aware, continual monitoring of mite populations is needed and some damage to emerging pasture and crop plants may have already occurred by the time sprays are applied. As with redlegged earth mites, weed control can suppress the build-up of blue oat mites during the growing season.

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