Redlegged earth mites are hatching and resistance testing is available
- Mingenew
- Minnenooka
- Boyup Brook
- Katanning
- Broomehill
- Cranbrook
- Ongerup
- Jerramungup
Redlegged earth mites (RLEM) have been found in roadside wild radish near Mingenew and Minnenooka.
Peak hatchings of RLEM have been observed at Boyup Brook, Katanning, Broomehill, Cranbrook, Ongerup and Jerramungup.
Growers with RLEM resistant to synthetic pyrethroids (SP’s) and organophosphates (OP’s) are closely monitoring their germinating canola crops. These growers are unable to use SP’s to control RLEM if damage occurs to the seedling canola. They are planning on applying Pegasus® only if crops cannot outgrow feeding damage.
Redlegged earth mite resistance
Resistant RLEM populations are likely to be present in paddocks that have a history of repeated insecticide applications.
Repeated use of the same insecticide groups, within seasons and between seasons, selects for RLEM to develop resistance.
Growers and consultants are urged to apply integrated pest management (IPM) strategies when managing RLEM due to cases of insecticide resistance in WA. These strategies include; identifying mites, rotating different chemical groups and reserving co-formulations or chemical mixtures only for situations where damaging levels of RLEM and other insect pests are present.
For more information see DPIRD’s Prevent redlegged earth mite resistance page and GRDC’s Resistance management strategy for the redlegged earth mite in Australian grains and pastures fact sheet.
Redlegged earth mite resistance testing in 2021
DPIRD, with co-investment from GRDC, will be undertaking RLEM resistance testing this year. If you notice RLEM surviving applications of insecticides please contact DPIRD technical officer Alan Lord or DPIRD research scientist Svetlana Micic to discuss and arrange for paddocks to be tested.
Correct identification of mites is important
It is easy to confuse mites so growers and consultants are urged to correctly confirm the identity of mites before making management decisions.
RLEM adults are 1mm long with a black body and eight red-orange legs. RLEM have a cold temperature requirement (generally seven days below 20°C average daytime temperatures) before the eggs are triggered to hatch. Immature nymphal RLEM are often a more reddish colour than when they are mature. RLEMs do co-exist with blue oat mites so be careful not to incorrectly diagnose the two mites. For more information refer to the DPIRD Diagnosing redlegged earth mite page.
Identifications can be made by using the DPIRD MyPestGuide Crops app which includes images and information of mite pests.
Alternatively, you can send images for confirmation through the PestFax Reporter app.
For registered insecticide recommendations for mites refer to DPIRD’s 2021 Autumn/Winter Insecticide Guide.
To read about previous mite activity this season refer to the 2021 PestFax Issue 1 article Bryobia mites are active. Can you identify the different species?
For more mite information contact Svetlana Micic, Research scientist, Albany on +61 (0)8 9892 8591 or Alan Lord, Technical officer, South Perth on +61 (0)8 9368 3758.
Article authors: Cindy Webster (DPIRD Narrogin) and Svetlana Micic (DPIRD Albany).