Now is the time to patch bait snails
- Manypeaks
- Gibson
Baiting is the recommended method for snail management. Timing of baiting is important and should coincide with active snail movement and feeding.
Snail movement is being monitored by the Stirlings to Coast Farmers (SCF) and South East Premium Wheat Growers Association (SEPWA). There are 2 cameras in the Albany port zone and one in the Esperance port zone. The snail movement project is being undertaken as part of the Grains Research and Development Corporation (GRDC) co-investment project ‘More effective control of pest snails in Australian Grain Crops (UOA2205-005RTX)’ led by the South Australian Research and Development Institute (SARDI), in partnership with SCF, SEPWA and the Department of Primary Industries and Regional Development (DPIRD).
With recent rainfall and dewy nights, snails have been observed actively moving beneath the cameras at Manypeaks and Gibson. Snails can become active after a rain event of 5 mm or more. Snails can also be actively moving, even if there has not been rainfall during the day, as long as humidity is above 75%. For more information see DPIRD’s Time snail baiting to coincide with maximum snail movement and before snails lay eggs page.
Before baiting entire paddocks, it is useful to patch bait to make sure snails are actively feeding. To do this hand broadcast baits in a small area and check for dead snails the next day.
Three steps for successful management of broadacre snails
1. Identify
There are 3 snail species that are pests of WA broadacre crops. For more information on how to diagnose snails refer to DPIRD’s Diagnosing snails in crops. It is important to know what snail species are in the paddock so the best methods of management can be applied at the right time.
2. Monitor
Snail numbers should be monitored to determine if they exceed DPIRD’s suggested threshold numbers and if there is a need to carry out management methods.
Snails are usually found on stumps, fence lines and under stubble, depending on the species of snail. Camera monitoring of snail movement has shown that the best time to check for snails in your paddock is early in the morning, from 6 am to 8 am, when there is moisture on plants and stubble.
A good way to determine snail numbers on open ground is to use a 32x32 cm square quadrant and count all of the live snails in it. This size quadrant is an area of 10% of a square metre so multiplying by 10 will give an estimate of snails per square metre.
3. Manage
Trials conducted by Stirlings to Coast farmers has shown that techniques such as cabling, speed tilling and stubble crunching that control round snails (white Italian, vineyard snail) are not effective on small conical snails. For more information refer to the Stirlings to Coast Farmers Trials Review Booklet 2020.
After sowing, baiting is the only control method for snails. Baiting before the crop emerges is more effective than after emergence as snails randomly encounter baits and are less likely to encounter plants to feed on. The less green plant material present in the paddock the more likely it is that snails will encounter a bait.
Baiting snails before eggs are laid will kill snails for the current season, in addition to decreasing the following years population.
It is hard to determine when egg lay will occur without dissecting snails to determine their level of sexual maturity. Dissections of small conical snails are being undertaken between February and May for a project led by the Stirlings to Coast Farmers (SCF) grower group, in collaboration with SEPWA and DPIRD. The initiative is funded by GRDC as part of its Snails Surveillance for the South Coast baiting program.
Dissection results can be viewed at the SCF’s South Coast Snails Monitoring portal. To date, snails in the monitored paddocks are all immature. It is expected that they will become sexually mature in the coming weeks. The team will be undertaking further dissections to confirm maturity during this time. Consultants and growers are advised to regularly check this website to see when snails are sexually mature in their area and bait before egg lay. If baiting occurs after egg laying, then plan to manage the next generation of snails.
An even spread of baits across paddocks also increases the chance that snails will feed on them, reducing the need for re-baiting. It is also recommended that growers’ budget for more than one bait application, a single application of baits may not be sufficient to control small conical snails. For more baiting information refer to the Stirlings to Coast Farmers Effective baiting options for the control of conical snails in the Albany port zone final technical report.
Research has also found that applying granular lime to a paddock with small conical snails increases shell strength and increase their fertility. Growers need to budget for baiting paddocks after liming has occurred. For more information see the GRDC Update Paper Determining the effect of lime on small pointed (conical) snail fecundity and shell strength.
A biocontrol program has commenced on the South Coast, where Australian-bred parasitoid flies (Sarcophaga villeneuveana) have been released to help control snail pests and protect crop yields, quality and growers’ profitability. For more information refer to DPIRD’s Fly biocontrol released to control farm snail pests media release. The fly re-release was augmented in February of this year at one site in the Albany and Esperance port zones.
Further information
For more information on slug and snail control visit:
- DPIRD’s Identification and control of pest slugs and snails for broadacre crops in WA page
- DPIRD’s Snail and slug control page
- DPIRD’s Managing snails in WA webinar recording
- DPIRD’s Managing snails in broadacre crops podcast
- GRDC’s Nail the Snails publication
- GRDC’s Snail baiting as part of an integrated pest management strategy video.
For more information contact Research Scientist Svetlana Micic, Albany on +61 (0)8 9892 8591.
Article authors: Cindy Webster (DPIRD Narrogin) and Svetlana Micic (DPIRD Albany).