Bryobia mites

Bryobia mites (Bryobia spp.) have been found in several paddocks around Colac, southwestern Victoria. The mites have been reported to be attacking lucerne, and have also been found in some pasture paddocks. The damage within pastures is difficult to assess because redlegged earth mite and lucerne flea are also present in high numbers. Eoin Flett (Williams & Jackson Ag services) has also recently observed bryobia mites in canola crops around Geelong and Bachaus Marsh, also in southwestern Victoria. The canola paddocks were sprayed for redlegged earth mites, but bryobia mites still persisted.

Initial findings by cesar indicate bryobia mites are significantly more tolerant to a range of registered chemicals than redlegged earth mites. Past experiences with bryobia mites in Western Australia reveal that alphacypermethrin is not effective as a control measure. Therefore other non-chemical control strategies should be considered, although more research into ‘selective or soft’ chemicals is needed.

The bryobia mite, often called the clover mite, is less than 1mm long with a fawn-orange coloured body and orange legs. In the field they are often mistaken for redlegged earth mites. Bryobia mites can be distinguished by their long forelegs which are 1.5 times the body length.

Eoin Fleet says bryobia mites were a sporadic problem around the Geelong area last season, causing considerable damage to barley crops in early winter. The mites were controlled with omethoate. Be on the look out for bryobia mites in newly established pastures and emerging crops.

Unfortunately, the biology and pest status of bryobia mites is poorly understood. The number of bryobia species that are agricultural pests within Australia is unknown. Unlike most other earth mite species, bryobia mites are most active in warm conditions in autumn, spring and summer. These mites are generally found in low numbers and are unlikely to be problematic over the winter period. They attack clovers, lucerne, lupins and canola. The feeding damage is characterised by a long trail of whitish-grey spots on the upper side of cotyledons and leaves.