g young crops and contaminating grain at harvest. Slugs can also cause significant damage to emerging crops.
Snails may feed on young crops, creating substantial bare areas that then need re-sowing. In late spring, snails can climb lentil plants and standing cereal stubble, contaminating the grain at harvest. The contaminated grain may be downgraded or rejected and live snails in grain pose a threat to exports. Crushed snails clog up machinery, causing delays during harvest.
Snails are dormant in summer, becoming active following rain in autumn. Young snails hatch about two weeks after rain initiates snail activity and egg laying. Multiple hatchings occur from May to October. They feed and grow through the winter and spring and then climb fence posts or plants in late spring, where they go into summer dormancy. Snails live for 1–2 years. They can move only short distances unless they are carried in hay, grain, machinery or vehicles.
Snail control starts in the summer before sowing, not at crop harvest. The first step in controlling snails is stubble management such as rolling, harrowing or dragging a cable on hot days or burning. Stubble management on hot days knocks snails to the ground where they dehydrate and die in the heat and rollers may also crush some snails. Air temperature needs to be over 35°C to kill injured snails and partial burning has a limited effect on snail numbers. These practices can impact on stubble retention systems and erosion vulnerability.
Conical snails are generally more difficult to control than white snails because conical snails shelter in cracks in the ground or under stones rather than on stubble. Dragging harrows or a cable before burning exposes more snails to the heat and improves the level of control.
The second step in the control program is to lay baits in autumn before the breaking rains initiate egg laying. Baiting snails in autumn will reduce egg laying (and the subsequent snail population) and reduce damage to young crops. Fence line baiting can be vital to prevent re-infestation of a paddock. To avoid contamination of grain do not spread baits within two months of harvest.
Windrowing of the mature crop can reduce the number of snails harvested as the snails are knocked from the crops during windrowing. When they re-climb plants, many are on the stalks between the windrows rather than in the windrow so they are not picked up by the harvester.
If snail contamination is so high that grain will be downgraded or rejected, seed cleaning equipment can be used to remove the contamination.
- Snail management fact sheet (GRDC)
- Bash ‘em, burn ‘em, bait ‘em: Integrated snail management in crops and pastures (SARDI).
Locusts and other pests of lentil
Australian plague locust (Chortoicetes terminifera) can cause significant damage to young lentil crops in some years. With suitable conditions, autumn swarms may migrate 200–500 km from south-west Queensland, north-west NSW and north-east SA into pastoral and agricultural areas where they lay eggs. From there a spring outbreak can occur within reach of lentil crops. See also 'Managing locusts in pulse crops'.
Other occasional pests of lentils include cutworms, balaustium mite, and clover (or bryobia) mite.
Cowpea and blue-green aphids can colonise lentil crops and spread viruses. See also 'Managing viruses in pulses'.
Refer to pesticide labels or the latest insect spraying charts for field crops and pastures available from various sources.
Native budworm larvae vary considerably in colour.
Native budworm damage to lentil seed.
Etiella moths have a distinctive 'beak'.
Once etiella larvae have entered the pod they damage most seeds and are protected from insecticidal sprays.
Redlegged earth mites (RLEM) cause the edges of leaves to turn brown and shrivel.
The red mark on the back distinguished the blue oat mite (pictured) from RLEM.
Snails can climb cereal stubble and be caught up in the harvest operation, potentially downgrading the grain.
Desiccation, harvest and storage
Chemical desiccation of lentil is sometimes necessary to ensure even ma