ths lay eggs on leaves, stems, flowers or pods. Large larvae (more than 1 cm long) cause significant damage as they burrow into pods and feed on the developing grain.
Budworm larvae can vary widely in colour, but all have a dark line down the centre of their back and a broad, pale stripe along each side of the body. Their skin appears bumpy. Stiff, short black hairs are usually evident along the body.
Weekly monitoring to detect larvae should begin at flowering. Increase to twice-weekly from early podding or from when moth activity has peaked. Sweep with a 38 cm diameter net 10 times in at least five different areas of the crop. Spray when five or more larvae are collected in any of the 10 sweeps. Delay spraying until the majority of larvae are about 1 cm long. Spraying too early increases the risk of a second population developing before harvest. Do not delay too long though because larger caterpillars require higher rates of insecticide and are the ones that bore into pods, causing the greatest economic losses.
Lodged lentil crops cannot be swept effectively. In lodged crops, shake half a metre of row vigorously over a white tray or fertiliser bag. Repeat 5–10 times. Control is warranted if an average of 1 larvae/m of row is detected.
See also ‘Managing native budworm’.
Etiella (or lucerne seed web moth)
Etiella (Etiella behrii) larvae bore into pods and mature while feeding on the developing seeds. When fully fed they exit to pupate in the soil. Controlling larvae is difficult as they remain inside the pods where they are protected from insecticidal sprays.
Management involves controlling the moths before they lay eggs. The moth has a slender body and a distinct beak. The wings are grey with a white streak along the front and a yellow band near the base. The wingspan is approximately 2 cm.
See also Etiella management in lentils (SARDI).
Snails and slugs
White snails (Cernuella virgata & Theba pisana) and pointed (or conical) snails (Cochlicella acuta & Cochlicella barbara) be a problem in lentil crops, damaging 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-i