Now is the time to patch bait snails
- Wellstead
- Gibson
- Dalyup
Dissections of small conical snails are being undertaken by DPIRD staff, agronomists, farmers and grower groups between February and May for a project led by the Stirlings to Coast Farmers (SCF) grower group in collaboration with the South East Premium Wheat Growers Association (SEPWA) and DPIRD. The Grains Research and Development Corporation (GRDC) is funding the initiative as part of its Snails Surveillance for the South Coast baiting program.
So far, snails dissected in Esperance had no green plant material in the stomach whereas snails dissected near Wellstead showed evidence of actively feeding.
During dissections in April of small conical snails collected near Gibson, Research scientist Andrea Hills (DPIRD) found green plant material in the snails’ stomachs. This indicates that snails in this area are actively feeding.
Dissections of snail albumen glands by DPIRD staff in April have also revealed that the albumen gland in snails at Gibson is increasing in size. The albumen gland in snails supplies the nutritive fluid required for egg production. For snails to be reproductive, the albumen gland needs to be developed. Monitoring the increase in albumen glands size indicates when snails will start laying eggs.
SCF has been coordinating dissections and to date, albumen glands in Esperance port zone are increasing in size, whereas in Albany snail glands are still very small. Snails in Esperance are not reproductive and laying eggs. As soon as there is widespread rainfall and glands become 4 mm or larger egg lay is expected to have occurred.
More dissection results can be viewed at the SCF’s South Coast Snails Monitoring portal.
Snail movement is being monitored by SCF and SEPWA as part of a project led by the South Australian Research and Development Institute (SARDI) and is an investment of GRDC. With recent rainfall, snails have been observed actively moving under the cameras.
Timing of baiting is important, to coincide with when snails are actively moving and feeding. Before baiting entire paddocks, patch bait to make sure snails are actively feeding. Baiting before egg lay occurs will decrease the following years population.
Biology & management of broadacre snails
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.
Eggs laid by snails this season will contribute to snail numbers next year.
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, fencelines and under stubbles, depending on the species of snail. Camera monitoring has shown that the best time to check is early in the morning, from 6am to 8am, when there is moisture on plants and stubble.
A good way to determine snail numbers on open ground is to use a 32x32cm square quadrant and count all of the live snails in it. This is an area of 10% of a square metre so multiplying by 10 will give an estimate of snails per square metre.
Trials conducted by Stirlings to Coast farmers has shown small conical snails are difficult to control with 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 as snails randomly encounter baits. The less green plant material is present in the paddock the more likely it is that snails will encounter a bait.
Timing of baiting is important, to coincide with when snails are actively moving and feeding.
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.
It is advised that growers patch bait sections of paddocks to make sure snails are actively feeding before baiting entire paddocks. An even spread of baits across paddocks increases the chance that snails will feed on them, reducing the need for re-baiting. If unsure that snails are actively feeding, consider baiting small patches and observe for any dead snails the day after.
It is also recommended that growers’ budget for more than one bait application. As 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.
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).
Article input: Lizzie von Perger (SCF), Andrea Carmody (SEPWA) and Michelle Handley (SEPWA).