Redlegged earth mites are hatching
- West River
This week an agronomist has reported seeing redlegged earth mites (RLEM) in a seedling canola crop at West River.
Growers are urged to monitor for RLEM activity in their paddocks and be wary of insecticide resistant populations.
Cesar Australia’s online RLEM egg hatch calculator has predicted hatching to occur within the first 2 weeks of May at Albany, Gnowangerup, Jerramungup, Ravensthorpe, Lake Grace, Wandering, and parts of the Great Southern Region. Early April hatching was predicted for areas east of Esperance and east of Albany.
RLEM insecticide resistance
Resistant RLEM populations are likely to be present in paddocks that have a history of repeated insecticide applications.
Growers and consultants are urged to apply integrated pest management (IPM) strategies when managing RLEM. 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.
Consider applying insecticides that are pest specific when spraying for pests other than RLEM.
For more IPM 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.
You can also listen to the DPIRD Grains Convo podcast Why aren’t your insecticides working on redlegged earth mite?
RLEM resistance testing in 2024
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 Research Scientist Svetlana Micic to discuss and arrange for paddocks to be tested.
Correct pest identification is important
RLEM and lucerne flea have different environmental requirements for hatching of over-summering (i.e. diapause) eggs and the difference in time can be important when considering insecticide application timing and length of efficacy such as post sowing pre-emergent sprays.
Correct identification of mites is also critical for effective control, as different species can vary in their susceptibility to certain insecticide groups, either naturally or through insecticide resistance.
RLEM adults are 1 mm long with a black body and eight red-orange legs. Immature nymphs are often a more reddish colour. For more information see DPIRD’s Diagnosing redlegged earth mite page.
RLEM can co-exist with and look similar to blue oat mites. For more information refer to DPIRD’s Diagnosing blue oat mites page.
Other common mites are bryobia (clover) mite and balaustium mite, but resistance has only been found in RLEM. For more information refer to DPIRD’s Diagnosing bryobia mite and Diagnosing balaustium mite pages.
You can request or confirm identification of mites by emailing the PestFacts WA team at pestfactswa@dpird.wa.gov.au.
Management of mites
Before spraying mites, consider if the crop is out-growing the feeding damage. In many years, and under good growing conditions, mites emerge from eggs during or after crop germination and the plants outgrow mite feeding damage.
For more information refer to DPIRD’s Earth mites - economic considerations for management page.
For registered insecticide recommendations for mites refer to DPIRD’s 2024 autumn winter insecticide guide.
Further information
For more mite information contact Research Scientist Svetlana Micic, Albany on +61 (0)8 9892 8591.
Article author: Bec Severtson (DPIRD Northam).