Balaustium mites

Balaustium mites (Balaustium medicagoense) have been reported from areas southwest of Melbourne, in the Central district of Victoria. Researcher, Aston Arthur (University of Melbourne), has been monitoring several paddocks and reports finding higher numbers of mites on warmer days, compared with sampling the same areas on cold days. Aston says this is typical behaviour of Balaustium mites, which are usually present in highest numbers in May and June, and tend to decrease over winter, before peaking again in spring.

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.

There are currently no chemicals registered for the control of Balaustium mites, and recent research results suggest they are more tolerant to a range of organophosphorus and synthetic pyrethroid chemicals compared with other mites. Therefore using label rates of pesticides registered for redlegged earth mites and blue oat mites is unlikely to provide sufficient control of Balaustium mites. Higher rates of a few synthetic pyrethroids have shown some efficacy against Balaustium mites in initial trials, however early control of late-summer weeds is probably the most appropriate option for preventing problems. Reports indicate that crops sown into paddocks with a pasture history and high levels of broad-leaved weeds will be most at risk from damage.