PEST MANAGEMENT DECISION GUIDE: GREEN LIST
Cutworms on lettuce
Agrotis segetum, A. ipsilon Cutworm
- Keep the nursery and field free of weeds as many weed species are hosts of cutworms
- Plough the field during dry spells, before transplanting, to expose the cutworm to natural enemies and extreme heat
- Remove and burn crop debris
before planting to reduce food for cutworms
- Conserve natural enemies such as ground beetles, lacewings, spiders, parasitic wasps, praying mantis, ants, and birds by avoiding the use of chemical pesticides if possible
- Delay transplanting slightly so that stems are as wide as possible (so cutworm cannot completely cut through them)
- If possible, flood the field for a few days before sowing or transplanting as this can help kill cutworm caterpillars in the soil
- Avoid planting host crops before/after or near lettuce field such as okra, leek, groundnut, peppers, melon, cotton. Cutworms attack a wide range of crops.
- Start monitoring for cutworms at seedling stage i.e. soon after germination. As cutworms hide during daytime and are mostly found on plants at night, the best time to look for cutworm is early morning.
- Look out for:
- Dry wilted lettuce, discoloured plants, or cut or fallen seedlings in a small zone
- Larvae - soft bodied, green to dark brown caterpillars at the base of the plant and on the underside of leaves. and
- Whitening or chlorotic lesions on leaves and dried leaves
- Blacklight and pheromone traps can be used to monitor numbers of adults/moths (2 traps/ha)
- Consider direct control when there are more than 5 larvae/10 plants in the farm
- Check and remove egg masses and caterpillars from plants and crush them
- Dig around the damaged plant to get the cutworms and mechanically kill them
- Flood the area to suffocate the larvae in the soil if you are growing lettuce in deep soils
- Mix equal quantities of sawdust, bran and molasses with enough water to make mixture sticky and spread around base of plants to attract and kill caterpillars
- Drench at seedling stage with Azadrachtin 0.03% (e.g. Nimbedicine EC, Nematech WG) at a rate of 35ml/L of water to reduce infestation drastically
- Natural extracts such as lemongrass and ginger can also be applied at 1 L/ 15 L water
- If available in your country, release Trichogramma weekly for 3 consecutive weeks at the first sign of moths to parasitize cutworms eggs.
CREATED/UPDATED: August 2017
PRODUCED BY: Plantwise
©CAB International. Published under a CC-BY-SA 4.0 licence.