il crops. Mite-damaged leaves have a rasped silvery appearance, turn brown and shrivel. Damage is most severe when cold, wet or dry conditions slow seedling growth.
Strategic prevention may involve foliar spraying in the previous spring. Clean cultivation in autumn and attention to weeds on fence lines is also essential. If possible, keep a distance from paddocks of the species that host mites, such as other pulses, pasture legumes (including sub clover and lucerne) and oilseeds, and control weeds such as thistles and capeweed along paddock borders and non-crop areas.
Bare earth insecticides that are registered in lentil for post-sowing use will protect germinating seedlings, when the crop is most vulnerable. Seed treatments work best when low numbers of mites are active during germination.
Monitor young crops weekly, inspecting lentil plants at 10 different sites within the crop. Weather conditions affect mite activity. If the weather is fine, estimate the numbers per leaf; if it is cold and cloudy, estimate the numbers per 100 square cm (10 cm x 10 cm) around the base of the plants. Mite damage is typically greater around the edge of paddocks where mites are invading from outside the paddock. An average of 50 mites per area inspected (leaf or around the plant base) indicates that control may be warranted.
The lucerne flea (Sminthurus viridis) is a small, wingless, light green, flea-like insect that jumps when disturbed. Symptoms of damage are a ‘window pane’ hole in leaves or ragged leaf edges. The host species range for flea is similar to that for RLEM. Control of lucerne flea is also similar to that for RLEM.
Monitor crops regularly, at least weekly, for signs of damage. If lucerne flea is suspected, look for the presence or absence of damage on 10 plants, repeated at five sites. An average of 10 or more holes per leaf may indicate that control is warranted.
Flowering and podding pests
Native budworm (Helicoverpa punctigera) moths migrate from inland Australia into lentil production areas in spring. Female moths 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, damagin