Brown wheat mites

Agronomist, Sarah Giblin (Giblin Agronomy Services), has observed small red mites present on some crops near Walgett, in the Upper Western district of NSW. The amount of feeding damage has been minimal, however, Sarah says the mites have been found in moderate numbers on wheat and barley crops in the region. The mites have been identified as the brown wheat mite (Petrobia latens) by Research Associate, Peter Crisp (Adelaide University). Agronomist, Rob Duncan (Landmark), has also reported recent problems with brown wheat mites near Roma, in south-east Qld.

Brown wheat mites are sporadic pests of winter cereals. They damage cereal plants by destroying plant cells as they feed, resulting in a stippling of the leaves. Brown wheat mites have a tendency to feed on the tips of the leaves, causing them to dry out and die. Heavily infested fields present a scorched withered appearance; attributes that can easily be confused with drought symptoms.

Adult brown wheat mites are globe-shaped, red-brown in colour and less than 1 mm in length. They have pale yellow-orange legs; their forelegs are distinctly longer than the other three pair of legs. The mites feed in the daytime, with activity on the plants reaching a peak about mid-afternoon. Click here to view a photo of the brown wheat mite for identification purposes.

The economic importance of these mites as a pest is unclear. Control may be considered if large numbers are concentrated on the flag leaf in times of moisture stress. Sarah says the mites in one barley crop have reached damaging levels and this crop has been sprayed with an organophosphate, which achieved adequate control. All affected crops will be closely monitored for the remaining season.