Modified cropping practices and chemical options will give graingrowers, particularly those in high rainfall areas, greater confidence in managing crop pests and grain contaminants in canola.

Supported by the Grains Research and Development Corporation, Svetlana Micic of the Department of Agriculture, Western Australia is developing better pest management systems, targeting species that are problems for growers and advisers.

A key component of the project is to develop grower friendly methods for monitoring major canola pests and assessing risk levels.

Bryobia and Balaustium mites and bronzed field beetle (BFB) larvae are major problems in southern areas, with some growers considering their control the most difficult problem in growing canola.

Laboratory work was undertaken to determine the biology of Bryobia and Balaustium, with populations maintained for several months as their behaviour and canola damage was observed.

Both bred continuously, even in summer conditions, explaining their early arrival in seasons with wet summers. Bryobia, however, damages emerging canola more than the more widespread Balaustium.

Adult BFB, which also contaminate grain during harvest, was sampled in standing and swathed crops, to help growers assess the risk of serious contamination and the need to clean grain. Later planted crops, coinciding with large BFB larvae, are more at risk.

Crops with plant residues have more BFB larvae and there is an indication that lupin and pasture residues are more favourable than cereal residues. GRDC supported trials are investigating this.

Time of harvest is also important, as day harvested crops contained less insect contaminants than night harvested.

More beetles moved under swathed crops than in those left standing, meaning grain harvested from swaths contained more insects. Moving the swath just before harvest greatly reduced insect contamination of grain.

Swathed material is highly attractive to BFB and other insects, especially when close to the ground. It is planned to investigate cutting the straw between the swath lines containing the grain and creating windrows close to the ground to act as alternative shelters for pests.

Chemical control options for early season canola pests will be tested, where necessary, so that appropriate chemicals are available.