Snails that are not controlled in autumn can damage pasture through winter and spring. Understanding the snail breeding cycle will ensure you are controlling snails at the best time for maximum impact.
Snails can create issues for pasture establishment in autumn or spring. They feed on wide variety of pasture and forage. If left unmanaged, snails can cause so much damage that you may even need to resow.
Crops and pastures grown on calcareous and highly alkaline soils are most susceptible to snails.
With any new pasture you need to check for pests weekly. One farmer in Western Victoria received a nasty surprise this year when he found the paddock had germinated but all the new pasture eaten by snails and slugs.
The impact of snail damage
This picture taken at Peterborough in Victoria shows snails having a good feed on established pasture. As shown here, snail damage in pasture shows as irregular pieces missing from the leaf edges. This damage also occurs in broadleaf plants.
Damage soon after germination may include the snails devouring the cotyledons, resulting in plant death as the plants are chewed down to ground level as they emerge.
Time control to match snail life cycle
During summer, snails rest under stones and stumps and in leaf litter. This period of resting is called aestivation. In summer, snails may also congregate on posts or plants to escape the high temperatures at the soil surface.
In the cooler temperatures of autumn, rainfall triggers the snails to break their resting phase and reproduce.
Rain-fast pellets are most effective when applied in autumn after moisture triggers mating and breeding among mature snails.
Juvenile snails feed throughout winter and spring.
Livestock will provide some control by trampling or accidentally consuming snails when grazing.
As a rule of thumb if you can see snails in daylight hours you may need to start a baiting program. An easy way to check numbers is put down a hessian bag or a square of cardboard overnight and check the next morning to see how many snails are huddled underneath.
Timing is critical for baiting. For the greatest impact, aim to spread bait when mating has been triggered by moisture, but before eggs are laid.
As little as 1 to 2 mm of rain can trigger snail activity.
How to control snail numbers
Rain-fast snail and slug pellets achieve the best results for controlling these pests in pasture.
Other options including weed control in neighbouring paddocks, and sowing methods.
GRDC Back Pocket Guide: Snail Identification and Control
Although it is intended as a resource for grain growers, GRDC Back Pocket Guide: Snail Identification and Control * also provides useful tips for effective integrated snail management in pasture.
GDRC Pocket Guide: Snail Identification and Control is available at www.grdc.com.au/BPG-SnailIdentificationAndControl