sustainability through science & innovation

Balaustium mites

Balaustium mites (Balaustium medicagoense) have been observed in unusually high numbers across many parts of Victoria over the last few weeks. Consultant, Simon Mock (Clovercrest Consulting), has reported Balaustium mites attacking a canola crop, west of Nhill, in the Wimmera district of Victoria. The paddock was pasture in 2011, and Simon reports the mites were found in higher numbers in areas where windmill grass and couch grass were present over summer. Simon mentioned that a pre-emergent spray of alpha-cypermethrin and a recent spray of gamma-cyhalothrin have not controlled Balaustium mites. Farm manager, Paul Wallace (Dookie), has reported Balaustium mites causing damage to emerging canola crops northwest of Shepparton, in the Northern Country district of Victoria. Paul also noted chemical control difficulties with mites.

Balaustium mites have also been found in high numbers around Colac, Geelong and Werribee, in the Western district of Victoria. Researcher, Aston Arthur (The University of Melbourne), says there has been a noticeable increase in Balaustium mite numbers over the past few years. It is unclear why this is the case although it may be related to the high natural tolerance this species has to insecticides. There are no insecticides registered for Balaustium mites and they will generally survive applications aimed at other mite pests in crops and pastures.

Balaustium mites are often confused with other mite pests. Adults reach about 2 mm long, and have a rounded red-brown coloured body that is densely covered with stout hairs, and eight orange-red legs. Balaustium mite damage appears as cupping and leathering of cotyledons, or irregular white spotting on cereals and grasses. Crops that are most vulnerable to attack include canola, lupins and cereals, as well as various pasture types. Correct identification of mite species is important before using insecticides. In addition to wasting time and money, the inappropriate use of chemicals can lead to issues with resistance and change the pest species dynamics.

PestFacts is supported by