Redlegged earth mites and blue oat mites

Redlegged earth mite (Halotydeus destructor) numbers are beginning to increase across many regions of Victoria and southern NSW. Reports have been made from several agronomists of high numbers of redlegged earth mites in pastures in the Riverina and South West Slopes district of NSW and in the Mallee district of Victoria. Agronomist, Tim Paramore (Tim Paramore Agronomic Services), has reported considerable feeding damage and high mite numbers in a phalaris sub-clover paddock near Walla Walla, NSW. Although this paddock was sprayed earlier in the season, Tim says another chemical application is needed to ensure some seed set of clover.

Redlegged earth mite numbers typically build-up in mid-late spring, so it is important to keep an eye out. Control of redlegged earth mites can be timed to occur during a short window of the season - during spring - before the production of diapause or ‘over-summering’ eggs. This approach will reduce redlegged earth mite numbers the following autumn. The timing of spraying is critical and dependant on location. Exact spray dates can be modelled and are freely available through a package known as Timerite®. For further information go to: www.timerite.com.au.

Consultant, Simon Mock (Clovercrest Consulting), has reported problems controlling blue oat mites (Penthaleus spp.) in an irrigated lucerne paddock, near Bordertown, in SA. Simon says the paddock was sprayed with dimethoate in late August. However, upon inspection of the crop a few days later, a significant number of blue oat mites were still present. A second chemical application has been necessary. This paddock has a history of chemical sprays to control redlegged earth mites, with Timerite® used over a number of years.

Blue oat mites are often mistaken for redlegged earth mites due to their similar appearance and sympatric life-cycle. Blue oat mites can be distinguished from other mites by their blue-black coloured body and characteristic red mark on their back. For images of blue oat mites click here.

This report serves as a timely reminder that correct identification of mites before deciding to spray in spring is important. Timerite® is designed only to control redlegged earth mites; this strategy will not effectively control other pests, such as blue oat mites.