Optimising slug management

WHY THIS PROJECT IS IMPORTANT

Slugs are becoming a major issue in the Riverine Plains region, with a recent run of good starts and wet seasons likely contributing to their appearance in new areas. Canola is widely grown across the Riverine Plains and is especially vulnerable to seedling damage by slugs. Where slugs are left unchecked, seedling damage can be extensive and crops may need to be resown. 

Because the economic cost to farmers of annual chemical control programs is significant, farmers are looking at ways to better understand and manage existing slug populations.

This project aims to investigate best practice to reduce slug damage in canola using chemical and non-chemical options. It involves the monthly monitoring of slug populations in dryland and irrigated paddocks located in NSW and Victoria, as well as the design and establishment of annual spring baiting trials, including non-chemical treatments, in collaboration with SARDI

Project focus

This project addresses the Riverine Plains strategic objectives of lowering production risk, optimising profitability and production, and increasing system sustainability and resilience.

The project involves a two-year chemical trial, through an investment by the GRDC, and a non-chemical component (2024), supported by the Victoria Drought Resilience Adoption and Innovation Hub.  

The two-year replicated chemical trial will evaluate spring baiting prior to sowing canola the following autumn. Treatments will include a control, as well as two different baiting treatments.

As part of the non-chemical component of the project, supported by the Victoria Drought Resilience Adoption and Innovation Hub, Riverine Plains conducted a farmer survey during 2024. The results are being used to better understand the presence or absence of slugs, the level of damage being experienced by farmers across the region, as well as the control practices that are currently being used. The survey results will inform activities for the second year of the project and are also being used to understand the potential for non-chemical slug control strategies to help farmers avoid the significant costs associated with chemical control.

This project  involves the monthly monitoring of slug populations in several dryland and irrigated paddocks located in NSW and Victoria. Extension events and activities will also support farmers in better understanding and managing their slug populations

Read the GRDC project report

Slug communities' response to environment and management across southern Australia

Monthly Slug Monitoring Reports

• December 2024
• October 2024
• September 2024

When and how to monitor for slugs

Monitoring slugs early in the season especially after rain or irrigation, when moist conditions favour slug movement and feeding. Refuge mats are a reliable and simple tool to assess slug pressure in cereal and canola paddocks. If you don't have access to slug mats, a hessian bag also works well. 

1. Soak the Mats
Soak the mats in a bucket of water so they’re damp. slugs are attracted to cool, moist shelters.

2. Place Mats in the Paddock
Spread the mats between crop rows or near stubble.
Choose multiple locations across the paddock, arranged in transects, to account for the patchy distribution of slugs.
In large paddocks (>  40 ha), aim for at least 50 mats to get representative data.
Secure each mat using bamboo stakes or tent pegs.

3. Leave Overnight
Place mats in the late afternoon or evening, as slugs are most active at night.

4. Check Safely
Next morning, remove pegs from one side only, then lift the mat away from your body in case of hidden pests (like snakes).
 
5. Record Observations
Count the number of slugs found under each mat.
Identify and record the slug species where possible (e.g. grey field, black keeled, striped field).
Record the results to help track activity and guide control decisions.
 
6. Monitor Regularly
Repeat monitoring weekly during crop emergence, or after significant rainfall or irrigation.
Even 1–4 slugs per mat can cause economic damage to cereals at seedling stages (GS00–GS21).