re of the potential for coloured foam marker dyes to stain lentil seed inside the pods.
Take note of the harvest withholding periods of the products used so that harvest does not need to be delayed because of product withholding periods. For paraquat the withholding period is 7 days on most labels. Crops that have been croptopped are more prone to seed staining after rain than crops that have been desiccated.
Weed wiping is being successfully used in lentil to prevent weed seed set of herbicide resistant ryegrass and other weeds. For weeds wiping to be successful, the in-crop weeds must be taller than the lentil plants, and any standing stubble) at the time of wiping.
A weed wiper can be useful to prevent seed set of tall weeds in lentils.
Lentils do not compete well with weeds but they do offer a variety of weed control options in the rotation.
Preventing seed set on all ryegrass escapes is the aim when croptopping in lentils.
The main diseases of lentils in Australia are ascochyta blight, botrytis grey mould and viruses. Integrated disease management in lentil requires the use of the following strategies:
- Paddock selection. Aim for a break of at least three years between lentil crops and at least 250 m from the previous year’s lentil paddock. Avoid sowing lentil in paddocks adjacent to faba bean, vetch, chickpea or lathyrus stubble as these crops can hosts diseases that affect lentils.
- Variety selection. Select varieties that are least susceptible to the main disease risk for the region. Sowing more than one variety spreads the overall risk.
- Seed source. Use seed from a paddock where there was no weed seed contamination and where no viruses and fungal diseases were previously detected. A fungal threshold of less than 1% is acceptable. For viruses, a threshold of <0.1% seed infection is necessary in high risk areas, and <0.5% seed infection for low risk areas.
- Seed treatment. Treat seed for sowing with a fungicidal seed dressing.
- Canopy management. Manipulate variety choice, row spacing, seeding rate and time of sowing to manage crop height, delay time of canopy closure and prevent lodging to assist in disease management. Wider row spacing (23–42 cm) delays canopy closure and may reduce disease, provided lodging does not occur. Standing cereal stubbles help to keep lentil plants erect but could enhance botrytis grey mould (BGM) development if stubble remains wet for long periods (e.g. 4–5 days). High humidity and excessive rainfall during the vegetative growth phases also could enhance the development of BGM and reduce seed quality.
- Sowing rate and depth. Target plant density should be 120–150 plants/m2. Aim for higher density populations for lower rainfall areas and short season environments. An ideal germination percentage is 80%, if less, sowing rates may need to be increased to compensate.
Seeding rate (kg/ha) = Plant density (plants/m2) x 100 seed weight (g) x 10 ÷ Germination percentage
Sowing depth should be 4–6 cm. This depth protects seed from herbicide damage and offers an optimum environment for rhizobium survival. Make sure there is good soil moisture before sowing and that seed has been inoculated.
- Sowing date. Sow within the optimal planting window for the district.
- Hygiene. Take all necessary precautions to prevent the spread of disease between paddocks and farms.
- Foliar fungicide program. Foliar fungicide applications often commence before canopy closure. Use the spray program for foliar fungicides provided below to assist in making fungicide application decisions. Success depends on crop monitoring, correct disease identification, timeliness of application and use of the correct product.
- Harvest management. Early harvest minimises disease infection on seed.
See also 'Meeting lentil market requirements'.
A BGM susceptible variety (front centre) showing botrytis grey mould compared with the same variety (immediately behind) treated with fungicide and other varieties (left and right) that have resistance to BGM.
Ascochyta lesions and leaf necrosis on lentil leaves.
Ascochyta staining on