Lentils emerge quickly from the soil compared to other pulses. This needs to be considered when applying post-sowing, pre-emergent chemicals. Ideally, control most weeds one week before sowing.
Before sowing use an effective knockdown herbicide combination such as Sprayseed® (2l/ha) and Bladex® (2L/ha). Trifluralin ® (1.5 L/ha) can also be used, but must be incorporated within four such hours of application otherwise it is ineffective.
Pre-emergent herbicide can be applied after sowing and has been sown at least 5 cm deep. Examples are Bladex® (2.0 L/ha) and Lexone®) (180 g/ha light sandy soils, 280 g/ha medium and 380 g/ha heavy [750g/kg active ingredient])
Post emergent herbicides available for managing broad-leaf weeds are Brodal (80-100 mL/ha applied after the 3 node stage) and Broadstrike (25 g/ha applied at the 4-8 leaf stage).
Note: The application of herbicides for broad-leaf weed control may cause crop damage if applied within 14 days of a grass selective herbicide.
Most grass weeds are easily controlled with a range of post-emergent selective herbicides. Select @ 250mL/ha + oil + wetta. Sertin, Sertin Plus, and Fusilade can be used.
Lifters used during harvest can dig into wheel ruts left by spraying vehicles so avoid spraying when the soil is very wet and use low-pressure tyres.
Redlegged earth mite During and following emergence Redlegged earth mite can infest and kill seedlings. As a precautionary measure, a bare earth insecticide can be applied pre-emergent after sowing which will provide up to six weeks protection against red-legged earth mite and lucerne fleas. As a precautionary step isolating the lentil crop from pasture or capeweed minimises the damage from Red-legged earth mite.
Following emergence and during early crop growth lucerne flea can infest plants. The damage appears as small windowpane like holes or as ragged edges on the leaves. This can stunt and set back the crop considerably.
Aphids (Aphis spp.) can damage lentil plants directly by feeding on plant tissue or they can act asvectors for the spread of virus diseases. Lentils are most prone to aphid infestation around flowering. Aphid infestation can be rapid, and the crop needs to be sprayed with an insecticide if aphids areobserved on 30 per cent of plants.
Lentils are very susceptible to native budworm damage from early podding through to pod fill. Monitor the crop for native budworm from late flowering. The crop will need to be sprayed if one or more larvae from 10 sweeps of a sweep net are found (this is equivalent to about one larvae per m2). Ideally, native budworm needs to be sprayed before they have grown to one cm.
Lucerne seed web moth (Etiella behrii) has caused damage to lentil crops in Victoria and South Australia resulting in downgrading of harvested grain due to poor seed quality. The larvae feed on seed producing ‘pinholes’ and chips. This insect is present in Western Australia and has been observed sporadically in pulse crops. It is unlikely that lucerne seed web moth will be a major pest of lentils, but may occur in some years.
Monitoring times for lentil pests and recommended pesticides.
Ascochyta blight and botrytis grey mould are the two most important diseases of lentils in Australia.
In Western Australia lentil crops are at most risk from ascochyta blight. This disease can reduce seed yields in susceptible varieties and decrease the value of the seed through discolouration. Serious yield losses from either ascochyta or botrytis grey mould have not yet been widespread in Western Australia, nevertheless crops must be carefully managed to minimise the risks associated with these diseases.
There are several steps to managing both ascochyta blight and botrytis grey mould in lentil:
- Choose the right variety. Current lentil varieties have good leaf-resistance to ascochyta blight, but the pods of most varieties have only moderate resistance or are susceptible. Northfield has both pod and foliage resistance to ascochyta blight, but does not yield as well as other varieties in Western Australia. Digger, Cassab and Nugget have moderate resistance to botrytis grey mould.
- Sow lentils on the same paddock no more frequently than one year in three. Don’t sow lentils more frequently than one year in three in rotation with chickpea, faba bean or vetch crops.
- Use seed with the lowest level of ascochyta infection available. Seed is a major source of ascochyta infection in the Western Australian environment.
- Ensure crops are at least 500 m away from last year’s lentil stubble and if possible up-wind.
- Always apply a fungicide dressing to the seed before sowing.
- Don’t sow earlier than the recommended sowing windows.
- Don’t create dense humid canopies in the crop by double sowing headlands or other areas of the crop.
- Apply a foliar fungicide at early flowering if disease is present. This is unlikely to increase seed yields for varieties with moderate ascochyta blight resistance, but will minimise the infection on pods and reduce seed discolouration.
Botrytis grey mould is more prevalent in warm and wet spring conditions where crop biomass is large and the crop canopy is dense.