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Snails

Regional coordinator, Jacob O’Brien (Dairy NSW), has reported conical snails causing feeding damage to pasture paddocks near Comboyne, in the Mid North Coast district of New South Wales. Jacob says the snails have heavily grazed ryegrass plants in large areas of each paddock, which contain remnant kikuyu stubble. Snails are present in high numbers; Jacob estimates densities of over 100 per m2. Snails are rarely observed in the Mid North Coast district. Entomologist, Kym Perry (SARDI) says moist and cool summer-autumn conditions over the past few years have resulted in a noticeable rise in snail populations and activity across much of southern Australia.

There are two species of introduced conical snails that are pests of grain crops and pastures in southern Australia. The pointed or conical snail (Cochlicella acuta) is rarely recorded attacking living plant material, but is regarded as a serious contaminant of grain. The species responsible for the damage at Comboyne is more likely to be the small pointed snail (Prietocella barbara). Small pointed snails have fawn, grey or brown conical shells and grow up to 10 mm long. They favour areas of rainfall higher than 500 mm. Crops grown on calcareous and highly alkaline soils are typically most susceptible.

Small pointed snails are a pest of pastures, lucerne, canola and pulse crops. Practices of stubble retention, reduced burning and minimum tillage assist snail populations to build up by allowing greater survival over summer. Because snails can be a contaminant at harvest, growers should be aware of receival standards for snails in different crop types, which are available from Grain Trade Australia or local grain traders.

Snails become active with the onset of cool and moist weather conditions in autumn, when they begin to feed, reproduce and lay eggs. It is important to monitor snail movement and population sizes on a regular basis as the timing for baiting is critical. Baiting is an effective option to control snails as part of a year round integrated approach that also includes cultural tactics over summer. However, it is critical to bait early enough in the season to control snails that are moving off their resting places but before they reproduce. Baiting for snails in late winter-spring is generally far less effective.

Stubble management, when used strategically over summer, is recommended in paddocks with high numbers and/or ongoing problems with snails. This includes cabling, rolling and slashing, which should ideally be performed on hot days over 35°C. Click here for further information on snail identification and management in crops and pastures.

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