PestFacts 16 November 2023
Summer management of snails
The most effective management of pest snails requires a year-round systems approach.
In spring, growers should determine if snails will be a problem during harvest, then implement strategies to deliver clean grain and start controlling snail numbers for next season. For spring management read Paddock practices: Snail management is a critical part of harvest preparation.
Summer management
Snails are vulnerable to dehydration and use refuges to survive hot and dry summer conditions. They over-summer above or below the soil surface on stubble, weeds, fence posts, rocks or other objects that provide a cool, moist habitat. Several cultural control methods exploit these vulnerabilities and can significantly reduce populations by removing available refuges and directly killing snails. They can be used repeatedly or in combination. However, decisions to use these tactics need to balance the trade-off between managing snails and the benefits of retaining stubble.
For a full overview read Nail the snails: A practical guide to integrated snail control for Australian grain growers.
Summer weed control
Reducing summer weeds is key for reducing numbers of many resident pest species. It is an important tactic to control snail populations and should be done before using other cultural controls as when summer weeds are present other control techniques are less effective.
Weed control should also occur in late autumn prior to baiting to reduce alternative food sources for snails.
Rolling, cabling and slashing
These tactics flatten stubble to reduce vertical refuges, knock snails onto the soil surface where many will dehydrate. It also can crush some snails.
Stubble bashing is most effective on hot sunny days with maximum temperatures above 35°C (ideally 40°C, when ground temperature is about 55°C), followed by more hot days. Always consider that the fire risk needs to be carefully managed. Repeat operations may be more effective in coastal areas with milder temperatures.
Grazing also flattens stubble, crushes snails and assists with weed control, and can be implemented any time between spring and autumn.
Baiting
While snails may become active on the soil surface after summer rainfall SARDI research has shown they do not always actively feed. Sample baiting after rainfall can be used to determine the extent of snail feeding and where to apply baits effectively.
The effectiveness of metaldehyde baits is also affected by temperature as they degrade in temperatures above 40°C. We recommend storing bait pellets in cool conditions over summer and avoiding hot sheds.
More information
Predicting next year's insect pests this harvest
Finding invertebrates such as snails, slugs, European earwigs, weevils and vegetable beetles during harvest can inform monitoring for next season.
Resident pests can live and build up high populations in paddocks over several years if conditions are favourable. Knowing hot spots or paddocks that contain these pests helps you make informed plans for next autumn, including where to monitor, crop choices and possible cultural controls. Take a note of what you’re finding in paddocks this harvest to know what to look out for next season.
Finding something doesn't mean you have to control it. Use this information to help you next season during monitoring activities. A hot dry summer can reduce some pest populations.
Reducing numbers during harvest
Some tips and tricks on how to stop the spread of resident pests and how to reduce numbers during harvest include:
- Clean your machinery before moving from one paddock to the next to minimise the risk of introducing pests into new areas. As cleaning machinery is time consuming and won’t remove all snails consider harvesting paddocks with snails last.
- Don’t harvest at night where there are known populations of nocturnal invertebrate pests such as European earwigs and black Portuguese millipedes as it increases risk of these pests being harvested alongside the grain.
- Check grain from swathed crops, as these tend to have more insect contaminants than grain from direct harvested crops. Invertebrates such as European earwigs and bronzed field beetle tend to congregate under crop swaths rather than in standing crops. The less delay there is between swathing and harvest, the fewer vagrant invertebrates are harvested with the grain.
- Check your chaff lines for invertebrate pests as they provide shelter and habitat.
- If you have snails in the paddock, use a stripper front during harvest to effectively reduce snail contamination as these fronts vibrate snails off standing cereals and take in less material. According to GRDC's Snail Management fact sheet, stripper fronts reduced snail contamination in grain by 50% compared to a standard open front.
Monitoring next autumn
A hot dry summer can reduce some pest populations so the spread of resident pests may have changed, especially if you undertook cultural controls removing habitat over summer. The information collected about hot spots or paddocks of concern gives you a starting place to look for known pest populations. Check under trash in the paddocks, around and on weeds, near fence lines, and within soil cracks as these are all refuges.
The original version of this article was published as Predicting next year’s insect pests this harvest.
Integrated Pest Management Checklist now available
The National Pest Information Network (NPIN) has released a new Integrated Pest Management (IPM) Checklist to demystify the processes involved in IPM and provide the Australian grains industry with clear, standardised advice.
Integrated pest management includes a range of management methods designed to suppress pest populations while reducing reliance on insecticides, especially prophylactic use and broad-spectrum products.
While the benefits of IPM strategies are widely recognised, on-farm adoption of management practices which align with IPM principles can be a challenge.
The aim of the checklist is to provide an overview of IPM practices and highlight which activities to focus on during different stages of the season. It is designed to be a tool in pre-season farm planning, a reminder of best practice, and a guide when responding to pests,.
The checklist has been designed to complement the WeedSmart Big 6 as a way to help drive the promotion and acceptance of IPM practice. It was developed by a team of entomologists and extension scientists, in close consultation with agronomists from each grains region. The checklist will continue to be updated and refined over time to ensure it accurately reflects actionable and achievable on-farm practices, based on feedback from industry.
NPIN welcomes you to complete the IPM Checklist feedback form about what would help industry implement or promote IPM.
For inquiries, please contact Dr Lizzy Lowe, Extension Team Lead at Cesar Australia at llowe@cesaraustralia.com.
The latest information for growers and advisors on the activity and management of pests in all broadacre crops during the winter growing season.
