Balaustium mites

Balaustium mites (Balaustium medicagoense) have been observed in high numbers across large parts of Victoria this season, and continue to cause significant issues. Agronomist, Ben Cordes (Tylers Hardware & Rural Supplies), has reported Balaustium mites in a barley crop east of Stawell, in the Wimmera district of Victoria. The paddock is under-sown with lucerne, although the mites are primarily attacking the barley. Mite feeding has caused yellow tipping of the leaf edges, with the first true leaf on some plants crimped and struggling to unfold. The paddock was pasture in 2011 with a forage sorghum crop over summer.

Research and Extension Officer, De-Anne Ferrier (BCG), has reported Balaustium mites causing issues in a canola crop near Horsham, also in the Wimmera district. The paddock was sprayed in mid June with bifenthrin at 100ml/ha, however upon inspection a few days later, the mites were still active. Correct identification of mite species is important before using insecticides. Applying insecticides at rates aimed at other mite species (such as redlegged earth mites and blue oat mites) will not be effective against Balaustium mites.

GRDC and cesar have recently developed a Back Pocket guide to aid in mite identification and control. Click here to view this free guide.

Given the increasing widespread reports of Balaustium mites it is recommended that paddocks with suspected ‘mite’ damage are closely monitored over several inspections. Vacuum sampling is an ideal way to assess the composition of mites present within a paddock. Over the last month, Philip Jobling (cesar) has repeatedly sampled a pasture paddock south of Geelong, in the Western district of Victoria. His experience highlights the importance of regularly and thoroughly monitoring pest mites. The species and density of mites varied considerably between samples, which were approximately 5-7 days apart. Philip said the time of day, weather conditions, soil moisture and the location within the paddock significantly influenced his collections. Basing management decisions on one quick inspection or a single sampling collection may not provide the best answer for the long-term management of a paddock.