In general, insects have not been a major problem in lentil production in Alberta. However, in the drier areas of the province, grasshopper and cutworm can sometimes be a problem.
Wireworm occasionally cause some problems, but only if lentil is seeded into a field that has had a forage grass crop included in the rotation. Other insects such as lygus and aphid are occasionally found in lentil but rarely at levels that justify the cost of using an insecticide.
- seedlings on the edge of the field can be attacked by grasshopper nymphs as they emerge in the spring, and damage can occur at both the seedling and flowering stage – if damage occurs at seedling stage, lentil will usually regrow from buds near or below the soil surface though maturity of these plants will be delayed
- greater damage occurs if lentil is attacked in the flowering to early podding stages – in this case, yields can be reduced by as much as 90 per cent
- seed contamination with grasshopper parts can result in reduced lentil quality since grasshopper heads are similar in size to lentil and are difficult to clean out
- with early seeding, lentil will normally grow past the susceptible stage before grasshoppers emerge
- Decis® (deltamethrin), Lorsban 4E® (chlorpyrifos), Pyrinex 480 EC® (chlorpyrifos and malathion 50 per cent) are registered for grasshopper control in lentil
- Decis® has greater activity in cool temperatures while malathion has greater activity in warm temperatures
- most cutworm damage occurs in late-May and early-June, usually at night, as larvae cut off seedlings just below the soil surface
- Ambush® (permethrin), Pounce® (permethrin), Decis® (deltamethrin) and Lorsban 4E® (chlorpyrifos) are all registered for control of cutworms in lentil
- spray at night, when the cutworms are feeding
- most wireworm damage occurs in early spring, when larvae are close to the soil surface
- larvae eat into the lentil seeds or damage young seedlings by eating them below the soil surface
- damage is rarely a problem unless lentil is seeded into a field that has had forage grasses in the rotation
- no insecticides are registered for wireworm control in lentil
- an insecticide seed treatment should be used for the first two years on cereal crops before lentil is seeded into a field that had forage grasses