What was it all about?

This project, which ran from 2017 to 2020, helped vegetable growers to develop practical approaches for pest control, building on previous research from Australia and around the world that shows pest populations can be influenced by field and landscape vegetation on farms.

The team developed a series of practical, evidence-based recommendations for growers, to guide crop placement in relation to other land uses adjoining the farm, and for weed control or promotion of riparian (water course) vegetation.

An initial survey of 491 fields of brassica vegetables, sweetcorn, carrot, lettuce, French bean and capsicum established that pest and beneficial arthropod densities are not uniform within each crop field and are strongly affected by nearby land use. Pest populations were lower in crops next to riparian vegetation, dams and roadways, but were higher next to other crops and weedy areas. Beneficial insects that attack pests were more numerous in areas of crops next to riparian vegetation and roadways.

The project team also conducted on-farm trials to investigate the use of flowering/companion plants within crops for pest control. Three annual plants (alyssum, buckwheat, and cornflower) were trialled in brassica crops in New South Wales, Victoria, Queensland and South Australia. Results showed that annual plant strips promoted an abundance of beneficial arthropods such as parasitic wasps and predatory beetles, with numbers elevated for up to 20 meters into the crop. The number of pests and pest-damaged crop plants were reduced, and parasitism of diamondback moth doubled. The cost ratios of nectar plant strips were as high as 8:1 in cases where the strips were accommodated in uncultivated areas, such as sprinkler rows.

One biennial plant (yellow rocket) was tested in additional trials as a trap crop to reduce egg laying by diamondback moth on brassica vegetable crops. These strips proved to be highly attractive to diamondback moth relieving the primary crop of pest pressure.

The team found that there is scope to influence relative densities of pests and beneficials in vegetable crops under Australian conditions. Pest management strategies should consider crop placement in relation to existing land uses, control of weeds, and the preservation and rehabilitation of water course vegetation. There are further benefits to be explored based on companion plants that can be established rapidly, rather than relying on slower-to-establish woody vegetation features such as shelterbelts.

The team shared its findings and recommendations in a series of industry-focused magazine and TV features, fact sheets, workshop and farm walk activities, leading to significant grower interest.

ACT NOW

Project findings and recommendations are available in these fact sheets and articles:

• Fact sheet: How does the surrounding landscape affect beneficials on your farm?
• Fact sheet: Boosting beneficials in your vegetable crop
• Article: Suppressing vegetable pests on your farm, Hort Innovation website, 22 February 2019
• Working with growers to secure a greener future, published in the July 2019 edition of Vegetables Australia, p38-39.